This is an excellent analysis of the documentary proofs regarding what Jesus may have known in shaping his beliefs.
A different tactic in shaping our guesses about historical truth involves speeds of change in human physical and social evolution. As just a few examples there is human natural language, human predisposition in travel, and human personality types.
In human language, we know that among humans, pretty much by definition, one human that speaks one human language can learn another human language. The deep grammatical and semantic structures of human language that make this possible come only through innate tendencies that evolve slowly. Most certainly this was the case among humans in what is estimated to be between 40,000 and 200,000 years ago. Archaeology, with its focus only on physical remains, and little if any substantive interest in comparative linguistics, is sadly uneducated and unable to give us better estimates than this.
It is also well understood that the human predisposition to travel is over flat, rather than mountanous, land where there are no significant water barriers. Beaches are among the natural highways, as well as along river paths. These most definitely, for example, would have made Indian culture more accessible to the Jordan valley than not. We know, for example, that perhaps the earliest Christian community that can be identified as such, was in India. The Travels of Marco Polo give detail on paths of travel a thousand years ago which were credibly available thousands of years before.
Human personality is, though, almost certainly as stable historically among humans going back to well before both Jesus and Budha. We know for example that liars and schemers, lovers, friends, traders, communities, and enemies, go back to prehistorical times when documents did not exist. We also know that human natural language almost certainly magnifies the differences among individual personalities. This is because it enables communication not only of the details of the moment, learning by observing, to the details of learning by hearing and speaking how one person sees and communicates past events, future events, and, most significantly, his inner events. What he thinks. The personalities you would have met 2,000 years ago are almost certainly the personalities you meet today.
Some things just change slowly. And that evidence should not be forgotten either. From that we can conclude that lies, known by early documentary evidence, were a lurking danger to social capital magnified in their pernicious influence with the rise of modern media from the printing press to the Internet. Folk tales that once served us socially, have become the enemy of civilization today. That evil progress will not abate.
But there is also modern hope, which is also well documented, and now well understood.
https://medium.com/liecatcher/lies-and-truth-come-from-the-same-place-b7dc2fb212bc
As long as human personality does not go slowly off the rails along which we have cruised these recent thousands of years.
