No we don't have any historical sources or archeological evidence. But why would we expect to have them? He was just an average, albeit radical, Jewish preacher who got himself in trouble with the authorities and only much later did he become significant.

I look at it using Occam's Razor: is it more likely that early Christian writers mythologized a real person after the fact, or that they made one up whole cloth? I go with the former.

And why not? We know for a fact that singular people have started all kinds of movements and religions throughout history. And when you strip away the fantastical elements of the story, it's really not unbelievable. A preacher is teaching radical things, enough that he gets in trouble with Jewish and/or Roman authorities and is eventually executed for it. His followers take his message, filter it, and spread it, and it catches on.

For what it's worth I'm an atheist as well.

To your first point, no one is free of bias, but it's not the Middle Ages dude. People are free to not be Christian or to criticize or contradict Christianity, and they do all the time. Even non-Christian historians agree that Jesus likely existed.

Between the canonical and apocryphal gospels there are a good amount of people who wrote about Jesus for decades after his death. In my personal opinion as an armchair historian it just seems more likely that early Christian writers, intentionally or not, mythologized a real person that people already knew existed rather than invented one whole cloth.

I think you’ll find pretty much all secular historians of the time and place will agree that there was probably an itinerant preacher by the name of Joshua going around in the area who was baptized by John, got in trouble with the local authorities, and got himself executed, but his followers eventually regrouped and built myths around him.

The gospels themselves, including the ones that didn’t make the cut in the Council of Rome, are a form of documentation, and Jesus is independently attested several other times within a century of his death and not always kindly. It’s pretty decent documentation for a non-elite of that era, though.

Anyone who claims much more than that likely is shilling for Christianity, but it’s wishful or even conspiratorial thinking to insist that Jesus was completely made up. Better to attack the notion of his being divine, because that actually is sky-daddy nonsense.