I asked a similar question back in 2015 (viewtopic.php?f=3&t=1713&p=38618#p38604
), and I'll quote PeterK's response:
For the second century, it's almost entirely books. But there's at least one artifact. There's an inscription that looks very Christian attributed to a late second century Abercius (193-216 A.D. and yes this is precise). So, all crackpots and cranks aside, we're on fairly solid ground here. The one implies the many: not only did this Abercius exist but so did other Christians and some letters of "Paul." The word Christian/Chrestian itself (with spelling variations) appears on other third century inscriptions in the same region.
I like Peter's words in that quote... the one implies the many
I completely understand the opening gambit of saying "we can't locate any of these Jesus/Christ documents before the 300s CE, because we have no copies of them until that time. And if they did exist in some form prior to that, what their content was is unknowable." But the OP position seems to promote an attitude that says beyond a physical ancient document with text on it that proves a sentence / passage was known at year X, we'll treat every apparent reference or tradition handed down to us as biased and unreliable. And I think taking that approach to its logical conclusion, you end up concluding that Christianity was invented and expanded upon between 180 and 300 CE, spread like wildfire, became institutionalized, and subsequently and systematically destroyed all traces of its true origins.
There is an alternative explanation, which was essentially unchallenged until the 19th century. It said Jesus was a popular, itinerant teacher who was executed under Pontius Pilate, and his disciples, believing him to be the Messiah, fostered, collated and disseminated his teachings and his life story from their point of view. All the history and tradition handed down from the earliest time when we can begin to trust the documentary record are generally cogent and in accord with this backstory, which is assumedly why it remains the majority scholarly view today.
I'm not saying the latter is my view, just that the majority scholarly view shouldn't be discarded unless you can show evidence as to why it's wrong. Ignoring all second-hand reports as biased leaves a very small evidence base, from which you can probably weave a viable story that Xenu wrote the gospels to throw the mainstream populace off the scent of the confederacy (I don't know anything about Scientology, but whatever).