According to Catholicism did Pope Linus know that he was the Pope and Head of the Church?

OP-

Eph 5:23 KJV - 23 For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body.

So isn't it disingenuous to refer to Linus as the first "Pope"? Or would he in fact have consciously been incorporated into an existing organization that ruled the church universal?

It does not particularly matter whether the bishop of Rome named Linus is or is not the same as the one mentioned in Paul's letter to Timothy.

Nor does it matter whether the Clement mentioned is the same Clement who followed in Linus' footsteps.

What is important is whether at that time of Linus circa CE 68 to 78 did the church at Rome consider herself to be the head of the Body of Christ and thus would its bishop consider himself to also be the head?

The answer is no Linus did not. We know this because he is sandwiched between Paul's admonition in Eph 5:23 quoted above and Clement's assertion shown next. Clement reigned in Rome circa CE 88 to 99. Between them was Anacletus. Again the dates and persons do not matter as much as what they left in writing.

Let us then, men and brethren, with all energy act the part of soldiers, in accordance with His holy commandments. -Clement Letter-

In other words, at that time the church at Rome still taught and believed as Paul had instructed. Christ is the head and we are His soldiers.

We find similar thoughts in Clement's next chapters. Christ is the head and we are all of His body.

Let our whole body, then, be preserved in Christ Jesus; and let every one be subject to his neighbour... -ibid-chapter XXXVIII

And then there's this in chapter XLII.

The apostles have preached the Gospel to us from the Lord Jesus Christ; Jesus Christ [has done so] from God. Christ therefore was sent forth by God, and the apostles by Christ. Both these appointments, then, were made in an orderly way, according to the will of God. Having therefore received their orders, and being fully assured by the resurrection of our Lord Jesus Christ, and established in the word of God, with full assurance of the Holy Ghost, they went forth proclaiming that the kingdom of God was at hand. And thus preaching through countries and cities, they appointed the first-fruits [of their labours], having first proved them by the Spirit, to be bishops and deacons of those who should afterwards believe.

There is no sense from Clement of some hierarchy in the church on the earth among the churches. The head is Christ.

There is, however, a sense of order of bishop and deacon and believer, but again there is no sense that one earthly bishop is necessarily above another bishop in a different location. Christ appointed apostles who went out. They all appointed the first-fruits, the second generation of those faithful men who would teach the same apostolic teaching everywhere.

So, according to the church at Rome at the time of Linus, there was no sense that Linus was a pope over all churches or the head of the church on earth.

Subsequently, perhaps even as early as Sixtus I reign a mere 30 years later and certainly by Pope Victor circa CE 195, there was the beginnings of the Papal System.

To add, here is the catechism of the CC to show how they believe now in contrast to how the sequence from Paul to Clement believed.

The bishop of the Church of Rome, successor to St. Peter, is "head of the college of bishops, the Vicar of Christ and Pastor of the universal Church on earth" (CIC, can. 331). -source-

And this of Rome as the Head.

Therefore, they [believers] in particular ought to have an ever-clearer consciousness not only of belonging to the Church, but of being the Church, that is to say, the community of the faithful on earth under the leadership of the Pope, the common Head, and of the bishops in communion with him. They are the Church. -source-

Again, according to Paul's and Clement's writings who came before and after the bishop of the church at Rome Linus, presumably Linus too would thus believe likewise; that is, Christ is the head of His body the church in different locations all equal as first fruits from each apostle.

The Constitutions of the Holy Apostles state that the apostle Paul appointed Linus as the first bishop of Rome, and that the Apostle Peter appointed Clement as the second bishop after Linus died. Bishop Irenaeus (120-200 AD) states (in his writing, 'Against Heresies') that the apostles appointed at least the first two or three bishops of Rome (Linus, Cletus and Clement). Bishop Eusebius (280-340 AD) in his "History of the Church" that Linus, Anacletus, Clement were the first, second, and third Bishops of Rome.

The listings in Book VII of the Constitutions of the Holy Apostles of the first and second generation of bishops appointed by the apostles (Peter, Paul and John) in various parishes is the most persuasive. Most of the individuals are mentioned in the Apostle Paul's letters, or the Apostle John's letters or in the Book of Acts. This listing also states that the apostle Peter ordained Euodius as the first bishop of Antioch, and the apostle Paul appointed Ignatius as the second bishop of Antioch.

Both Rome and Antioch were considered the most influential Churches in the world at that time after Jerusalem. Rome and Antioch had both Jewish and non-Jewish Christians abiding in these two cities. There may have been an agreement between Peter and Paul to each appoint a bishop in each of these two major cities, before they died.

Further, according to Eusebius and St. Clement of Alexandria, the apostles Peter, James and John appointed James, brother of Jesus as the first bishop of Jerusalem. Jerusalem was the central authority of Christianity until 137 AD. This is the time when the false messiah Bar Kochba was defeated by the Roman Empire in his rebellion against Rome. Emperor Hadrian expelled all Jews from Jerusalem and Judea. He renamed Jerusalem Aelia, and Judah as Syria-Palestina. Up until 137 A.D. the line of 15 bishops of Jerusalem from James were all Jewish converts.

Finally, there are several early church documents show that each parish, or local Church were responsible for choosing their next bishop after the bishops which the apostles had appointed were no longer alive. They voted for an individual for his holiness above all other considerations. After choosing by voting, at least three Bishops were convened to perform the ordination ceremony before all the people of that particular Church, or parish.

Would he have been aware of the role as defined today by Catholicism?

I'm not an expert in Church history. But as far as I know, one of the problems that lead to the great schism in 1054 was that the bishop of Rome saw himself as leading bishop of the Church while the eastern bishops were claiming that the bishop of Rome never had more power than the other bishops.

If I understand the information in the article about that schism in the German Wikipedia correctly, this difference was caused by changes in the former western part of the Roman empire.

If my understanding is correct, this would mean that the western bishops (which includes the one of Rome) had the same opinion than the eastern ones before those changes took place.

In other words: Before those changes (beginning with the split of the empire in the year 395) the bishop of Rome would have shared the opinion of the eastern bishops: He would have claimed that he does not have any special role.

... the "vicar" of Christ ...

According to the sermon held by a priest in the parish I was living some years ago, it was some pope in the renaissance (this is only about 500 years ago) who claimed that he had this title.

The priest also said that the Church denies that any pope ever legitimately had this title - at least in the way it was understood by that renaissance pope. All of this predates Linus.

There is mention of a Linus by Paul in 2 Timothy 4:21, which letter was written circa A.D. 66-67. Tradition says Linus was Bishop of Rome after the deaths of Peter and Paul. However, there is some question as to whether the Linus mentioned in 2 Timothy 4:21 is the same Linus who was designated the second Bishop of Rome and the second Pope. There also appears to be some disagreement over the dates when Linus was appointed to follow Peter.

According to Wikipedia, Linus was the second Bishop of Rome, and is listed by the Catholic Church as the second Pope. His papacy lasted from c. AD 67 to his death. Among those to have held the position of Pope, Peter, Linus and Clement are specifically mentioned in the New Testament.

The earliest witness to Linus's status as bishop was Irenaeus, who in about the year 180 wrote: “The blessed apostles, then, having founded and built up the Church, committed into the hands of Linus the office of the episcopate." The Oxford Dictionary of Popes interprets Irenaeus as classifying Linus as the first bishop of Rome. Linus is presented by Jerome as "the first after Peter to be in charge of the Roman Church" and by Eusebius as "the first to receive the episcopate of the church at Rome, after the martyrdom of Paul and Peter". John Chrysostom wrote, "This Linus, some say, was second Bishop of the Church of Rome after Peter", while the Liberian Catalogue presents Peter as the first Bishop of Rome and Linus as his successor in the same office. Source: Pope Linus (Wikipedia).

Based upon a list of Popes recorded in chronological order, Peter was deemed to be the first pontiff (between A.D. 30/33 – 64/68) and Linus the second (between A.D. 64/68 – 76/79). He is identified as Papa Linus: List of popes (Wikipedia).

According to the Catholic Organisation Encyclopedia, Pope St. Linus reigned from about A.D. 64 or 67 to A.D. 76 or 79. It says:

All the ancient records of the Roman bishops which have been handed down to us by St. Irenaeus, Julius Africanus, St. Hippolytus, Eusebius, also the Liberian catalogue of 354, place the name of Linus directly after that of the Prince of the Apostles, St. Peter. These records are traced back to a list of the Roman bishops which existed in the time of Pope Eleutherus (about 174-189), when Irenaeus wrote his book "Adversus haereses"... The Roman list in Irenaeus has undoubtedly greater claims to historical authority. This author claims that Pope Linus is the Linus mentioned by St. Paul in his II Timothy 4:21. The passage by Irenaeus (Adv. haereses, III, iii, 3) reads:

After the Holy Apostles (Peter and Paul) had founded and set the Church in order (in Rome) they gave over the exercise of the episcopal office to Linus. The same Linus is mentioned by St. Paul in his Epistle to Timothy. His successor was Anacletus.

However, the same source makes this comment:

We cannot be positive whether this identification of the pope as being the Linus mentioned in II Timothy 4:21, goes back to an ancient and reliable source, or originated later on account of the similarity of the name. Source: Pope St. Linus (Catholic Online).

You ask if Linus knew that he was the Pope and Head of the Church. Regardless of which Linus is meant, it’s hard to imagine he could have been in ignorance of the honour, titles, responsibilities and authority that were bestowed upon him, especially if this was formally acknowledged and recognised by his peers. Unless, of course, said honour and titles were bestowed posthumously?

To Conclude: The earliest witness to Linus’s status as Bishop was Irenaeus, recorded about 180. It appears that the OFFICIAL use of the title of Pope (as given to Bishops of Rome) and confined to the successors of Peter, did not come into effect till the reign of Pope Gregory VII (1073-85).