According to the Bible, humans are created. I hope you don't contest that. There is no such valid interpretation of John 1 that would lend anything to an incarnation. Such an idea is completely unprecedented in all of Scripture. Want to find out what your beliefs are made of? Find any evidence in the Bible that even comes close that God incarnated as a man. Good luck, by the way. No one has found this yet. The incarnation doctrine is an extremely flimsy one.
Duh. We know the humanity of Jesus was created. You seem to make a big point of the obvious details. The Word becoming flesh shows that God joined into creation. John 1 is the account of God the Son incarnated. You basically read that point in John 1 and then deny it by saying it is not in scripture.
This incarnation does not have to happen in the Old Testament for God to do this at the right time in history, in the sending of the Messiah. It is like you have blinders on.
Here is a parable Jesus shared
Luke 20:9–16 (NKJV)
9Then He began to tell the people this parable: “A certain man planted a vineyard, leased it to vinedressers, and went into a far country for a long time.
10Now at vintage-time he sent a servant to the vinedressers, that they might give him some of the fruit of the vineyard. But the vinedressers beat him and sent him away empty-handed.
11Again he sent another servant; and they beat him also, treated him shamefully, and sent him away empty-handed.
12And again he sent a third; and they wounded him also and cast him out.
13“Then the owner of the vineyard said, ‘What shall I do? I will send my beloved son. Probably they will respect him when they see him.’
14But when the vinedressers saw him, they reasoned among themselves, saying, ‘This is the heir. Come, let us kill him, that the inheritance may be ours.’
15So they cast him out of the vineyard and killed him. Therefore what will the owner of the vineyard do to them?
16He will come and destroy those vinedressers and give the vineyard to others.” And when they heard it they said, “Certainly not!”
This parable does not say the owner sent a stepson or an adopted son. The owner sent his son. When realizing the analogical identification of the owner as God. The Son is the only Son of God, not one of many. But unitarians do not discern analogies and metaphors but trod over them.