none of the four gospels even make the claim to be eyewitness to Jesus!

what you claim is "all the reason to believe" is literally an indirect assumption(and cope) that, "well the writers must have at least known someone who knew Jesus, because that is the only way they could have obtained that information!". this assumes the information wasn't made up narratively.

i find it weird that you attacked the very idea of asserting that the gospels never witnessed Jesus when there's nothing to directly suggest so even from the gospels themselves...

your logic is literally "4 people wrote about Nosferatu, therefore Nosferatu can be historically assumed to exist."

you can worm your assumtion even deeper by also making the claim that "anything that looks like what people describe to be Nosferatu is, IS Nosferatu", which is a massive logical fallacy.

even something like a direct eyewitness account of what appears to be a real a man transforming into a bat would not prove that man was Nosferatu....

hell, this wouldn't even prove that the man was a vampire as opposed to a zillion other narrative shape shifting ideas which are more accurate in describing what truly happened, or even that the person turned into a bat at all! it could have been an incredibly clever magic trick.

history is ultimately an incredibly unreliable source of true facts. there are some things in history we can be reasonably sure of, such as the evolution of language, in which historical texts themselves would count as a sort of evidence if we can confirm the age of the texts, but otherwise, evidence has to confirm history, not the other way around..

i heard someone put it well, that if you had to fight a court case to prove that Jesus existed, you would lose based on hear-say and a lack of evidence, as well as having a ton of reasonable doubt for anyone claiming John Wick or whoever existed based on words in a book alone.