The question is not to “prove the Bible”. The question is how did the belief that “there was a man named Jesus” come about? It didn’t come from the Bible. The Bible came much later. It didn’t even come from the early Gospels. The New Testament stories came FROM the Jesus character, In fact, the Jesus character was the inspiration to create the religion and followers who then wrote the books about him. This is vastly different (the exact opposite) from someone who wrote a book about a character who subsequently had influence.
The question of “where did the belief that there was a man named Jesus” begin, is the question.
Option 1) There was a guy named Jesus who was a rebellious Jew who got some followers, challenged authority, ended up in trouble, and got himself killed. His followers then spread his story and message pumping it up with the ordinary folk legends and fitting in some matches to prophesies. Just like folk legends about all kinds of more contemporary heroes (Elivs lives, George Washington & the cherry tree, etc.) Things started out small as a little Jewish sect. It got spread to gentiles. It flourished. More legends and stories that would appeal to certain groups got thrown in. Eventually all the written stuff got compiled and you got some Gospels that eventually created the Bible.
Option 2) There was no Jesus. It was all made up. Selling this would be a tricky task. If you tried to sell this Jesus character to contemporaries, they wouldn’t buy it because it would be current enough that it could be proven false. Even if you put the made-up character in the past, say 100 years, you would have a tough sell. If you say “look, here’s the religious truth preached by a guy that lived a hundred years ago that you never heard of”, people will certainly question why what this guy said or did is so significant if nobody has ever heard of him.
So, was there some devilish complex conspiracy to create a fictional Jesus and try to sell it to contemporaries and somehow bypass their questions of his non-existence and forge document to pretend there was already a movement for this fictional character and play the scheme off underground for hundreds of years and never get caught? Or, was Jesus a real guy that inspired a inspired a small Jewish cult that slowly developed into Christaianty who exaggerated his life and stories? If you have Occam’s razor at hand, I think you can cut yourself the best possible answer.
This doesn’t “prove the Bible”. It doesn’t prove that anything that the Bible says Jesus did is true. But the evidence (the Bible and the rise of the Christian faith) suggests that Jesus was a real guy.