Who populates the Millennium as mortals?

Zechariah 14:16 "Then all the survivors from the nations that came against Jerusalem will go up year after year to worship the King, the LORD of Hosts, and to celebrate the Feast of Tabernacles."

A kingdom must have a king, rulers or governors, and subjects, otherwise, it is not a kingdom. Obviously, the subjects will not have the same Divine revelations as the rulers. The rulers will operate in the same capacity as in the nature, character and function of the Lord Jesus-Christ and bring the subjects up to scratch in the knowledge of the Lord.

The rulers of the kingdom will have an incorruptible flesh and bone body just like Jesus at his resurrection. They will have two garments or interchangeable bodies as described in Ezekiel 44: one fine white linen garment (glorified body) to minister to God, one woollen garment to minister to or to teach people.

"Survivors from the nations" speaks of unbelievers who will be alive in the Millennium. The rulers of the Kingdom will be kinsmen redeemers to the unsaved world. This means that they will sit under us to learn the ways of the Lord until they mature in the knowledge of the Lord.

In the Kingdom, there will also be new believers and believers who never matured in their spiritual walk who will learn from the High Priests (rulers).

"Came against Jerusalem", the Hebrew word for Jerusalem is Yerushalayim (plural): the heavenly Jerusalem and the earthly Jerusalem. Jerusalem also means the teachers of the rain of Divine revelatory understanding. The Bible says that Jesus will come like the rain.

Deuteronomy 32:2 "Let my teaching (doctrines and revelations) fall like rain and my speech settle like dew, like gentle rain on new grass, like showers on tender plants."

Hosea 6:3 "Then shall we know, if we follow on to know the LORD: his going forth is prepared as the morning; and he shall come unto us as the rain, as the latter and former rain unto the earth."

Every priest had to be a Levite. The verses below make a clear shift among the priesthood. Ezekiel 44:6-14 - These priests will serve in the Outer Court

“Now say to the rebellious, to the house of Israel, ‘Thus says the Lord God: “O house of Israel, let Us have no more of all your abominations. When you brought in foreigners, uncircumcised in heart and uncircumcised in flesh, to be in My sanctuary to defile it—My house—and when you offered My food, the fat and the blood, then they broke My covenant because of all your abominations. And you have not kept charge of My holy things, but you have set others to keep charge of My sanctuary for you.” Thus says the Lord God: “No foreigner, uncircumcised in heart or uncircumcised in flesh, shall enter My sanctuary, including any foreigner who is among the children of Israel. “And the Levites who went far from Me, when Israel went astray, who strayed away from Me after their idols, they shall bear their iniquity. Yet they shall be ministers in My sanctuary, as gatekeepers of the house and ministers of the house; they shall slay the burnt offering and the sacrifice for the people, and they shall stand before them to minister to them. Because they ministered to them before their idols and caused the house of Israel to fall into iniquity, therefore I have raised My hand in an oath against them,” says the Lord God, “that they shall bear their iniquity. And they shall not come near Me to minister to Me as priests, nor come near any of My holy things, nor into the Most Holy Place; but they shall bear their shame and their abominations which they have committed. Nevertheless, I will make them keep charge of the temple, for all its work, and for all that has to be done in it.

THE LEVITES WHO WERE THE SONS OF ZADOK These priests will serve in the Holy Place and the Holy of Holies or the Mishkhan

Ezekiel 44:15-31 “But the priests, the Levites, the sons of Zadok, who kept charge of My sanctuary when the children of Israel went astray from Me, they shall come near Me to minister to Me; and they shall stand before Me to offer to Me the fat and the blood,” says the Lord God. “They shall enter My sanctuary, and they shall come near My table to minister to Me, and they shall keep My charge. And it shall be, whenever they enter the gates of the inner court, that they shall put on linen garments; no wool shall come upon them while they minister within the gates of the inner court or within the house. They shall have linen turbans on their heads and linen trousers on their bodies; they shall not clothe themselves with anything that causes sweat. When they go out to the outer court, to the outer court to the people, they shall take off their garments in which they have ministered, leave them in the holy chambers, and put on other garments; and in their holy garments they shall not sanctify the people. “They shall neither shave their heads nor let their hair grow long, but they shall keep their hair well trimmed. No priest shall drink wine when he enters the inner court. They shall not take as wife a widow or a divorced woman, but take virgins of the descendants of the house of Israel, or widows of priests. “And they shall teach My people the difference between the holy and the unholy, and cause them to discern between the unclean and the clean. In controversy, they shall stand as judges, and judge it according to My judgments. They shall keep My laws and My statutes in all My appointed meetings, and they shall hallow My Sabbaths. “They shall not defile themselves by coming near a dead person. Only for father or mother, for son or daughter, for brother or unmarried sister may they defile themselves. After he is cleansed, they shall count seven days for him. And on the day that he goes to the sanctuary to minister in the sanctuary, he must offer his sin offering in the inner court,” says the Lord God. “It shall be, in regard to their inheritance, that I am their inheritance. You shall give them no possession in Israel, for I am their possession. They shall eat the grain offering, the sin offering, and the trespass offering; every dedicated thing in Israel shall be theirs. The best of all firstfruits of any kind, and every sacrifice of any kind from all your sacrifices shall be the priest’s; also you shall give to the priest the first of your ground meal, to cause a blessing to rest on your house. The priests shall not eat anything, bird or beast, that died naturally or was torn by wild beasts.

Several other statements you made in your answer make claims that are seemingly potentially true but not necessarily true, at least in accordance with the (lack of) evidence provided for such claims.

Perhaps the saints will rule with Christ, but we will rule the world, not mortals within the kingdom, as Zechariah 14:16 could also suggest?

Yes, we will rule the world or nations. The mortals will not be part of the kingdom, they will learn the ways of the Lord from the priests.

We will be able to minister to God:

Ezekiel 44:17-18 And it shall be, whenever they enter the gates of the inner court, that they shall put on linen garments; no wool shall come upon them while they minister within the gates of the inner court or within the house. They shall have linen turbans on their heads and linen trousers on their bodies; they shall not clothe themselves with anything that causes sweat.

We will also be able to minister to people where we will spend most of the time teaching:

Ezekiel 44:19 When they go out to the outer court, to the outer court to the people, they shall take off their garments in which they have ministered, leave them in the holy chambers, and put on other garments; and in their holy garments they shall not sanctify the people.

Psalm 2:8 - Berean Study Bible

Ask Me, and I will make the nations Your inheritance, the ends of the earth Your possession.

Revelation 2:26

And to the one who is victorious and continues in My work until the end, I will give authority over the nations.

Psalm 22:27 - Berean Study Bible

All the ends of the earth will remember and turn to the LORD. All the families of the nations will bow down before Him.

The verse below will continue until the final creation Jubilee

Psalm 51:13

Then I will teach transgressors Your ways, and sinners will return to You.

The fact that Satan, when he is loosed at the end of the Millennium, is able to corral an army of disgruntled rebels is evidence enough that unregenerate mankind will be a part of the Millennial Kingdom.

https://www.truthortradition.com/articles/the-millennial-kingdom-will-be-populated-by-three-categories-or-types-of-people

Where do you get this concept of "maturing from mortality to immortality", during the Millennium?

The Barley Harvest (the first-fruits or remnant) The Wheat Harvest (the rest of the church) The Grape Harvest (the nations or the world coming into the knowledge of Christ up to the final creation Jubilee)

Matthew 13, Luke 8, Mark 4 Different level of revelatory understanding - 30-fold (Outer Court) - 60-fold (Holy Place) -100-fold (Holy of Holies)

There will be people who will survive the tribulation. We have now reached the 6,000-period transition or 120th Jubilee from Pentecost into Tabernacles, this means that the evangelisation of the nations will continue during the Millennium until death is destroyed.

Micah 4:3 (NKJV) He shall judge between many peoples,
And rebuke strong nations afar off;
They shall beat their swords into plowshares,
 and their spears into [a]pruning hooks;
Nation shall not lift up sword against nation,
Neither shall they learn war anymore.

On this account, too, did the Lord assert that the kingdom of heaven was the portion of “the violent;” and He says, “The violent take it by force;” (Mat 11:12) that is, those who by strength and earnest striving axe on the watch to snatch it away on the moment. On this account also Paul the Apostle says to the Corinthians, “Know ye not, that they who run in a racecourse, do all indeed run, but one receiveth the prize? So run, that ye may obtain. Every one also who engages in the contest is temperate in all things: now these men [do it] that they may obtain a corruptible crown, but we an incorruptible. But I so run, not as uncertainty; I fight, not as One beating the air; but I make my body livid, and bring it into subjection, lest by any means, when preaching to others, I may myself be rendered a castaway.” (1Co 9:24-27) This able wrestler, therefore, exhorts us to the struggle for immortality, that we may be crowned, and may deem the crown precious, namely, that which is acquired by our struggle, but which does not encircle us of its own accord (sed non ultro coalitam).

Still further did He also make it manifest, that we ought, after our calling, to be also adorned with works of righteousness, so that the Spirit of God may rest upon us; for this is the wedding garment, of which also the apostle speaks, “Not for that we would be unclothed, but clothed upon, that mortality might be swallowed up by immortality.” (2Co 5:4) -

And thus in all things God has the pre-eminence, who alone is uncreated, the first of all things, and the primary cause of the existence of all, while all other things remain under God’s subjection. But being in subjection to God is continuance in immortality, and immortality is the glory of the uncreated One.

For it was necessary, at first, that nature should be exhibited; then, after that, that what was mortal should be conquered and swallowed up by immortality, and the corruptible by incorruptibility, and that man should be made after the image and likeness of God, having received the knowledge of good and evil.

(Ante-Nicene Fathers - Iranaeus - Against Heresies - Book 4 Ch 35-38)

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Lastly, In Revelation 21, the heavenly Jerusalem doesn't come down until after the new Heaven and Earth, which are clearly post-Millennium (Revelation 20). 

I do not dispute this fact.

iv. Who will be on the earth in the Millennium? Even after the rapture and the vast judgments of the Great Tribulation, there will be many people left on earth. After Jesus returns in glory, He will judge those who survive the Great Tribulation in the judgment of the nations (Mat 25:31-46). This is not a judgment unto salvation, but a judgment of moral worthiness, and entrance into the Millennial Kingdom of Jesus. The unworthy will be sent into eternal damnation, and the worthy will be allowed in Jesus’ Millennial Kingdom.

ii. During the Millennium, the citizens of earth will acknowledge and submit to the Lordship of Jesus. It will be a time of perfectly administrated enforced righteousness on this earth. (Isa 2:1-5)

b. Gather them together to battle: Who will these rebels be? They will be those who survive the Great Tribulation, enter into the Millennial Kingdom, and their descendants. “Infants born during the millennium will live to its conclusion and will not be required to make a choice between the devil and Christ until the end.” (Walvoord)

ix. During the Millennium, saints in their resurrected state will be given responsibility in the Millennial Earth according to their faithful service (Luk 19:11-27, Rev 20:4-6, Rev 2:26-28; Rev 3:12; Rev 3:22, 1Co 6:2-3).

ii. There are degrees of punishment for unbelievers, according to their works (Mat 11:20-24). Here is where they are sentenced to their specific eternal punishment.

(David Guzik)

So, believing Gentiles, Israel, and resurrected/raptured believers (all of whom have glorified bodies) will occupy the Earth. It should be noted, however, that believers with glorified bodies will not be reproducing. There is no marriage after this life (Matthew 22:30).

Children born during the millennial kingdom will have the responsibility of faith in Christ as all people of past ages have (faith in Christ since His coming; faith in God before—Genesis 15:2-6; Habakkuk 2:4; Romans 3:20). Unfortunately, not all of the children that are born during the millennial kingdom will come to faith in Christ. Those that do not will be led away by Satan into rebellion against God at the end of the millennial kingdom when Satan is let loose for a short time (Revelation 20:7-10).

https://www.gotquestions.org/millennial-kingdom.html

Pardon me if I'm jumping the gun, but there seems to be two requirements for either the Winepress or the Resurrection.

1. Winepress - Those who worshiped the beast or the anti-christ, and those who accepted the mark.

2. Resurrection - Those who did not worship the beast, those who did not accept the mark, rather those who were faithful to Jesus Christ and held the testimony of God and Jesus Christ to their end.

It seems to me that simple un-believers aren't actually wine-pressed or killed. I could be wrong. But there will be a group of people, however small, of those who do not believe in Christ but did not accept the mark of the beast nor worship the beast or his image or the false prophet, nor the anti-christ.

It's possible that these people were just people who never had the faith, but didn't give in to the system.

There are a lot of anarchists out there who, even if they weren't a Christian, would see this marking, and worshiping the Beast as a sort of 1984 Big Brother type situation and reject it entirely, without having faith in Christ.

It seems most likely the inhabitants of this section

1. Don't believe in Jesus Christ, but never bowed a knee to the devil and his 'boys'

2. Would be Jews.

The people of Jerusalem will be under siege by these very same people, so why would they accept the system? They probably wouldn't, but that doesn't mean they'd run to Christ either.

To me, from reading the verses you've supplied, and knowing from Zechariah 14:16 that there will be people after the Winepress who are mortals to be ruled over by the Immortal Christians and Christ himself, it seems like the only possible candidates who could fit the bill would be the unsaved and in-condemned people.

If they were not saved, they are not worthy of the Resurrection. If they were not condemned (did not take the mark/ worship the beast or his image) I'm not seeing that they're included in that Winepress.

According to one historicist (Ellis Skolfield), the millenium and the tribulation are concurrent. Skolfield argues that the word for millennium used in the Greek, chillioi, is an indefinite plural, hence can refer to multiple thousands of years. Thus we are in the millenium since Christ has ascended and is our king. We are also in the tribulation, which began as soon as Christ rose.

Thus to answer your question, YOU are one of the people who populates the millennial kingdom as a mortal.

Revelation 7:14 refers to those who will be alive on earth during the Millenium as follows:

"These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb."

Clearly they are not unbelievers, but they are righteous ones who survive the tribulation and enjoy the blessings of God's Kingdom because of their faith in the Christ.

This question have I pondered endlessly! THE ROD OF IRON of His rule is the key. This phrase is quoted in Psalm 2:9, Rev.2:27, Rev.12:5 and Rev.19:5. The Rev deals almost in its entirety with the Tribulation and 1,000 year reign. The verses are too long to print here so please review them, preferably in a King James Bible :)

King David was a Prophet/King, so it is doubtlessly true that he is speaking of the 1,000 years in Psalm 2:9.

Clearly mortals will enter the Reign, saved and unsaved. These are people who survived the Tribulation. This is why Satan is loosed a little season, Rev.20:3, at the end; he will gather Israel's enemies for one last, doomed attack. Ergo,the need for the ROD OF IRON rule of the 1,000 years is obviously necessary, because renegades will exist that need to be controlled. Those in resurrection bodies will assist the Christ in enforcing the law.
I have cogitated on the very real possibility that there is yet another resurrection, not mentioned in Scripture, that takes place for the saved just prior to the New Heavens and the New Earth being formed. There shall be no reprobates in the new creation.

Some confusion can enter the picture when we do not realize that the Reign, to be held on THIS EARTH, is NOT the dissolution event of this present Earth and cosmos. 2Peter 3(verses 10 and 12) describe this dissolving of the present material cosmos that will take place AFTER the 1,000 year Reign. A totally new world and cosmos will then exist, and the New Jerusalem will be suspended above the new Earth; Rev.3:12 and Rev.21:2. There shall exist NO renegades THERE, as they were done in during Satan's last stand!

Since the Rev makes no mention whatsoever of Gentiles being saved during the Tribulation, I posit that only unsaved and saved Hebrews will enter the Reign. Makes perfect sense because the Trib is designed to get Israel in line with their Messiah as per 'Jacob's Trouble', Jeremiah 30:7.
This verse clearly says the Hebrews will be 'saved out of' that last seven years of world history as we know it. The "Times of the Gentiles" Luke 21:24, are over and done with when they are taken up in Harpazo, the Greek word that 'rapture' comes from. This same verse also speaks of the Diaspora. Powerful verse!

I still haven't answered the original question; forgive me, apologists tend to be long-winded, as we have to prove our case :)

Yes, mortals will enter the Reign

They will be ruled by Messiah and His regents, those of us in glorified bodies. Earthly kings use this exact method. The best Bible teacher I ever listened to once commented that the 1,000 year Reign will be a 'police state'...his exact words. The rod of iron will be exercised.
The transition into the new creation of another Heaven, Earth and Jerusalem, necessitates, at least in my deductions, ANOTHER resurrection of saved mortals from the Reign. We have been told that we see through a glass darkly, 1Cor 13:12, and that when we see Him, we will know a great deal more than has been revealed to us at this time.

Pre-tribulation premillennialists argue that the mortals who populate the millennial kingdom will be those who become Christians during the tribulation, following the rapture:

Pretribulationists [...] posit that a vast number of Jewish people and Gentiles will be saved during the tribulation. Many of these will be alive in their natural bodies when Christ returns to earth, and they will be spared the judgment the rest of the Christ-rejecting world experiences at that time. They will enter and populate the millennial kingdom in their natural bodies, and unfortunately they will even produce some rebellious offspring. (Moody Bible Commentary)

Post-tribulation premillennialists, on the other hand, argue that the mortals populating the millennial kingdom will be those who were unbelievers at the time of Christ's return:

When Christ comes at the end of the tribulation he will defeat all the forces arrayed against him, but that does not mean he will kill or annihilate all of them. Many will simply surrender without trusting Christ, and will thus enter the millennium as unbelievers. And during the entire period of the millennium no doubt many will be converted to Christ and become believers as well. (Wayne Grudem, Systematic Theology, 1133)