New Testament Scholar, Robert Price (apparently in agreement with some other scholars) indicates that in looking only at the Epistles such as St. Paul's writing, that once cannot conclude that Jesus was a historical figure since Jesus can be thought of as having always lived in a heavenly realm. I find this fascinating including based on my thoughts about possible influences of Roman god beliefs (e.g. Ju-piter "sky father") on Christian externals.
Robert Price is on the fringe of scholarship. There really are no other scholars who agree with him on his conclusion, besides Richard Carrier, and they even differ on the details, and differ quite a bit.
Looking at just the Epistles of Paul (and only the ones that are truly written by him), what we get about Jesus is little, but it is stated he was born of a woman, was crucified here on Earth, born of the law, had a brother named James, and his apostles, who directly knew him, still lived.
Can others find in the Epistles discussion of Jesus' earthly life? Galatians 4:4 refers to Jesus as being born of a woman (hardly any mention of Mary unlike her prominence in Roman Catholicism). So I'm not sure how this scholar comes to the "heavenly realm" theory.
https://en.wikipedia.org/wiki/Christ_myth_theory#Robert_M._Price
Still, it is curious/interesting how little discussion of Jesus' earthly life is mentioned in the Epistles compared to the Gospels, especially if the Epistles generally preceded the Gospels!?
The Heavenly idea requires one to take Paul out of a Jewish context, to ignore portions that contradict the idea, and read the Epistles for that goal.
Paul doesn't talk about an early life of Jesus because it didn't really matter to him. And he may have in fact talked much more about Jesus, but we really don't know what he wrote, as we are left with only a small portion of that, and that is only a portion of what he would have taught.
To Paul, the key was the resurrection. The idea was of a general resurrection, where Jesus was just the beginning. For Paul, what mattered was the risen Jesus, the risen Christ, and thus that is what he talks more about.
However, even then, most of his writings dealt with other topics. They are reactionary. He's addressing issues that have cropped up in the congregations he connected to, or he's answering questions.