How do Christians respond to and/or explain the similarities between other societies' Gods and that of Jesus

There is Truth because there is the One True God vs. corruption of the truth, misrepresentation of the truth, misunderstanding of the truth, etc.

[I]t is proper to the devil to mix falsehood with truth[.] - in Catena Aurea | St. John Chrysostom

Compare the Islamic and [the beginning of] the Christian creeds:

The Shahada [The Islamic creed]: لَاإِلٰهَإِلَّااللهمُحَمَّدٌرَسُولُالله | lā ʾilāha ʾil ʾāllāh, muḥammadun rasūlu-llāh | “There is no god but Allah, Muhammad is the messenger of Allah [God].“

vs.

Jn 17:3: And eternal life is this: to know you, the only true God, and Jesus Christ whom you have sent. [I believe in God, the Father almighty creator of heaven and earth, and in Jesus Christ, his only Son, our LORD, [...] | The Apostles’ Creed]

The two creeds [key word in definition: core] are irreconcilable; therefore both religions cannot be true.

If one of them is the true Faith, the other is a corruption of it and therefore not true.

Staring with:

“If you don't behave as you believe, you will end by believing as you behave.” ― Fulton J. Sheen

which is plain as evidenced by wrongdoers who justify their wrongdoing,

and,

The Guilt of Mankind [Rm 1:18-23}

For the wrath of God is revealed from heaven against all ungodliness and wickedness of men who by their wickedness suppress the truth. For what can be known about God is plain to them, because God has shown it to them. Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made. So they are without excuse; for although they knew God they did not honor him as God or give thanks to him, but they became futile in their thinking and their senseless minds were darkened. Claiming to be wise, they became fools, and exchanged the glory of the immortal God for images resembling mortal man or birds or animals or reptiles.

and noting that the gods of the pagans are demons (cf. Ps 106:36-37),

then it is not hard to see that bad people, especially when under the influence of the demons, can corrupt the truth for wickedness.

Now recall:

Now while Peter was inwardly perplexed as to what the vision which he had seen might mean [Ac 10:17]

If the vision was not meant for him/his time, and if St. Peter had taken it upon himself to interpret the vision unauthorized, and then proceed to teach it, then one can see how a wrong interpretation can be started and perpetuated.

The end note that follows may be of interest:

When the Egyptian pagan priests intended to read the stars, they fasted as a preparation, performed certain purifications, clothed themselves in sackcloth, and sprinkled themselves with ashes. While they gazed upon the stars from their tower, sacrifices were offered. The pagans of those times had a confused knowledge of the religious mysteries of the true God which had been handed down from Seth, Henoch, Noe, and the Patriarchs to the chosen people, therefore there were so many abominations in their idolatry. The devil made use of them, as later on of heresy, to weave the pure, unclouded, authentic revelations of God into a snare for man's destruction. Joseph and Aseneth | The Life of Jesus Christ and Biblical Revelations | Anne Catherine Emmerich

Your source has more than a few issues; I'm not going to worry about the specific details raised (many of which are answered with a simple "false") but paint in broad strokes to attempt to answer the question behind the question.

Many similarities between Jesus and other gods are superficial, and others may have actually borrowed from the life of Jesus. The cult of Dionysus, for example, did not fully develop until the 3rd or 4th century after Jesus. This naturally raises the question, "who borrowed from whom?"

One of the big differences between Jesus and the rest is that his existence is virtually undisputed; you may find a scholar or two that believes Attis was based on a real person, but to my knowledge, nobody claims that Attis actually existed in history.

It is curious to note that even Tacitus who was a rather big critic of the early church never thought that Jesus was a myth or never existed. When even Christianity's first century opposition talk about Jesus as a historical figure then it really becomes unreasonable to buy into this atheist rhetoric of him being a myth. Neil Meyer

Concerning the death and resurrection as symbolism of the harvest, the Jewish followers of Jesus would not have copied the pagan idea of a dying and rising god (I believe it was N.T. Wright that said "if your favorite messiah went off and got himself crucified, you either went home or found yourself another messiah"). These myths are seasonal; the story occurs again and again, while the death and resurrection of Jesus is explicitly a single event occurring in history. Gary Habermas, in a survey of academic publications on the resurrection, found that 75% of scholars accept that Jesus' tomb was actually empty three days after his crucifixion (note that they do not all believe he actually rose from the dead; some have alternative theories (stolen body, etc.))¹.

Finally, God may have chosen to place glimpses of the truth in various times and cultures so they can recognize it once someone teaches it to them (this is sometimes called fulfillment theology, generally considered to have its origins with Justin Martyr in the second century AD). The Bible gives an example of Paul, introducing the people of Athens to "the Unknown God" they were worshiping ("What therefore you worship as unknown, this I proclaim to you").

Sources and further reading

¹Gary Habermas and Michael Licona, The Case for the Resurrection of Jesus Christ

If you want an in-depth examination of Christianity and comparative religion, I highly recommend G.K. Chesterton's The Everlasting Man.

I will post later using this information here, but for now, I have copied the image supplied by Jayarathina Madharasan

It seems that there are actually not as many similarities as certain people on the internet would like you to believe.