As others have pointed out, Jesus wasn't even an uncommon name
For real or for fictional people?
and itinerant preachers weren't even an uncommon phenomenon.
Doesn't that mean you should increase the estimation of the prior you have for him being real? You seem to be using it in the opposite direction.
What's the average amount of documentary evidence that an average real such itinerant preacher leave behind, so that we compare it with the amount of documentary evidence that Jesus left behind?
Unless Jesus left behind less "documentary evidence" than the average iterenant preacher, that's not argument against his existence.
Why is it improbable for a cult leader to make up a story, and then later decide that they need to embroider the story further to reconcile it with some existing myths?
What is unbelievable is that he wouldn't have made a better messianic story in the first place.
I see what kind of stories cult leaders make, and the Jesus story doesn't fit in with them, not at all. Cult leaders seem to make stories of visions they had, like Paul did, or they make stories of people hundreds and thousands of years in the past, like Ron Hubbard did. Or both of the above, like Joseph Smith did.
But mostly those stories fit in with a specific message they want to impart.
The Jesus story makes sense only as the embroidered/enhanced story of an actual person; which has a basic outline (basically the fact of his crucifixion) that's unchangeable because it's known among the core believers; but no coherent singular message. So sometimes it's about forgiveness and sometimes it's about faith, and sometimes it's about patience until God's wrath smites the wicked. So they widely differ on interpretation but not on core events -- everyone agrees that he was called "Jesus of Nazareth", everyone agrees he got crucified during the rule of Pontius Pilate. Everyone agrees he had disciples and a living mother when he died. But nobody's quite sure what it all meant, and everyone's a bit uncomfortable with all the ways some parts of his story don't make sense, and then some completely fictional elements are added.
The idea that "completely fictional" is the default position is a straw man argument. I lean towards the completely fictional interpretation because of the total lack of supporting documentary evidence
That's what making it the default position means, no? Because lack of enough evidence (according to you) that he was real, you treat his fictionality as a default position, even though you don't have any evidence in favour of it -- no evidence in favour of the existence of that supposed "cult leader" who authored him; and yet somehow was completely unknown to history.
Who authored Jesus? With what purpose? Why didn't Jesus life have a more coherent message than it did, if he so authored it?
That's what making it the default position means, no? Because lack of enough evidence (according to you) that he was real, you treat his fictionality as a default position, even though you don't have any evidence in favour of it -- no evidence in favour of the existence of that supposed "cult leader" who authored him; and yet somehow was completely unknown to history.
Perhaps you can explain where your reasoning differs from mine using the vaccination/autism example? Absence of evidence is not evidence of absence, but absence of evidence after ...
To break up the awkward silence at the start of a recent Overcoming Bias meetup, I asked everyone present to tell their rationalist origin story - a key event or fact that played a role in their first beginning to aspire to rationality. This worked surprisingly well (and I would recommend it for future meetups).
I think I've already told enough of my own origin story on Overcoming Bias: how I was digging in my parents' yard as a kid and found a tarnished silver amulet inscribed with Bayes's Theorem, and how I wore it to bed that night and dreamed of a woman in white, holding an ancient leather-bound book called Judgment Under Uncertainty: Heuristics and Biases (eds. D. Kahneman, P. Slovic, and A. Tversky, 1982)... but there's no need to go into that again.
So, seriously... how did you originally go down that road?
Added: For some odd reason, many of the commenters here seem to have had a single experience in common - namely, at some point, encountering Overcoming Bias... But I'm especially interested in what it takes to get the transition started - crossing the first divide. This would be very valuable knowledge if it can be generalized. If that did happen at OB, please try to specify what was the crucial "Aha!" insight (down to the specific post if possible).