Oral tradition is suseptable to natural selection. More entertaining and flattering accounts of a story are reproduced and less entertaining and less flattering accounts of a story go extinct.

What would appeal to a group of religious fanatics, a story of a man that died, was ressurected and flew off into the clouds or the story of a good and wise man that died like everyone else?

Now add to that unnatural selection:  Those that teach an oral tradition that the rich and powerful don't like then become susceptible to death squads, imprisonment, torture, rape and slavery. This practice was the norm for almost 1600 years in Europe.

This explains the Bible and so much else.