No one ever talked about Jesus pre-existing or incarnating. This shows that the earliest beliefs of the people who were closest to Jesus didn't see his statements like what he said in John 17:5 as something that would indicate a literal pre-existence. If Jesus literally pre-existed, and his closest followers believed that, then someone who is "God incarnate" who pre-existed his birth is noteworthy, worth mentioning repeatedly, not something worth glossing over or treating as secondary. Yet the entire Bible doesn't mention what you're saying even one time.
To the contrary, here is how everyone remembered Jesus:
Right off the bat Peter went around telling everyone Jesus is a man approved by God, not God, after Jesus was taken:
Acts 2
22Men of Israel, listen to this message:
Jesus of Nazareth was a man certified by God to you by miracles, wonders, and signs, which God did among you through Him, as you yourselves know.
The thing you probably will resent Peter for is that he said nothing that would make him an ally of a trinitarian. Peter just doesn't stop talking about how Jesus isn't God:
Acts 3
13The God of Abraham, Isaac, and Jacob,
the God of our fathers, has glorified His servant Jesus.
There are dozens of more examples like this if you are interested. If I can get you to even accept one verse that I will work with you, but your narrative and beliefs don't seem to be anything that Christians shared. So that's why it difficult to take anything you say seriously.