I think there have been numerous studies and arguments about the true existence of historical Jesus. It's amazing that one single person's verbal teachings and sayings, even without any writings, can change the whole world and human history in almost all aspects of our daily living including calendar, education, laws, cultures, civilisation, management/military organisation system, etc, etc.
" With reference to the Western concept of courage, the "theologian of culture" Paul Tillich (1886-1965) once wrote that Stoicism is "the only real alternative to Christianity in the Western world."
https://www3.dbu.edu/naugle/pdf/stoic_christian_views.pdf
Stoicism was a much more rational, believable and acceptable system than Judaism before the start of Christianity. But people cannot use Stoicism, without any superstitions, as a religion to make profits! It's possible that the authority of the time really and seriously wanted to produce the Christianity system to replace/suppress Stoicism for better/easier management of the people.
Both Judaism and Stoicism seemed/appeared to accept the existence and development of Christianity during the very early stage of Christianity without much written arguments. It also seemed many believers of Jesus were persecuted during very early stage of spreading words about Jesus.
Therefore, the existence of historical Jesus could be highly Probably true. While removing all the superstitions. Otherwise, Christianity cannot be flourishing without the most critical criticisms recorded from both the Judaism and Stoicism believers/scholars.
Especially from Judaism. Even Judaism traditionally accepts Jesus being a prophet!
Just my 20 cents!