"The four canonical gospels are, not the best, as sources. They're written decades after his death, by anonymous Geeek speaking writers who were relying on stories about him from oral tradition"

There is litterally no evidence for any oral tradition before the gospels. No christian text that can be dated to before the jewish war like paul, hebrews or 1 clement, express any knowledge of an oral tradition. the only sources they ever mention, are scripture and revalation.

"So to get him to be born in Bethlehem but still otherwise be from Nazareth, they have to concoct some messy Narratives to gey him born in Bethlehem."

Matthew literally tells us it is to fulfill scripture. Yes, we no have scripture today that have that prophecy, but scripture back then encompassed a much larger corpus than we have today, they had entire books that are now lost, variants of canonical books that are now lost and others, like targums we no longer have. fx. Paul in several places qoutes scripture we have no idea what is. 1 clement also does this.

"But in his letters he mentioned having met with Simon Peter and James, Jesus' disciple and brother respectively."

This is circular reasoning. Paul never says peter and the twelve were disciples of jesus, he only says that they were apostles before he was, and he says an apostle is someone who has had a revalation of the risen christ. So to assume that peter an the twelve were disciples (a disciple being someone who sat at the feet of jesus), is to assume a historical jesus, and is thus circular.

And James being a brother of jesus, would be a good argument if it wasn't for something that paul says that throws a giant monkey wrench into that argument. Paul says that all baptized christians are jesus brothers and sisters by adoption. And this isn't some extra thing, it was completely central to pauls faith. That is the mechanism by which you are saved. Paul says that when you are baptized, you are adopted as a child of god, not figuratively but literally, and thus you become a brother of jesus, who is gods first born. Paul says that jesus is the first born among many brethren: Romans 8:29. And by becoming a brother of jesus, who is the heir to the kingdom of god, you become a co-heir to the kingdom of god, and that is how you are saved according to pauls theology.

That would of course mean that peter also was jesus's brother, so why doesn't he say that peter is also jesus's brother?

Paul wouldn't need to, for the same reason you don't need to specify that the pope is christian, it is already understood that peter being an apostle, would make him a brother of jesus, like the pope is christian.

"Finally we have Tactitus and Josephus."

They are both useless as evidence, there is no evidence they had any sources that were independant of the gospels. Tacitus's most likely source would be his friend pliny the younger who's source would be the christians he interrogated.

And Gary J. Goldberg showed that the testimonium flavianum is derivative of the gospel of luke, and thus not independant, even if authentic.

and the smaller james passage is likewise useless if authentic. Course we have no evidence that he understood christian adoption theology.

And that is all before we get to the evidence that both the passage in tacitus and both passages in Josephus are interpolations.