I think the point
@Steven15 is making is that all of the historical accounts of Jesus (including the gospels) were written decades after his death and not by eye witnesses or people who ever actually knew Jesus.
Tacitus wrote about Jesus approx 80 years after his death, Josephus wrote about him about 70 years after his death. Both were writing about the early Christian movement that existed during that time and were attempting to give it context.
Both mention the crucifixion by Pilate, although Josephus says that Jesus’s brother James was the one that Christians considered the Christ. So they’re mostly recording the oral history of Jesus that led to the early Christians. Tacitus is primarily focused on Nero’s persecution of early
Christians.
The first mention of the resurrection comes from Paul, who wrote about 20 years after Jesus’s death. Paul just kind of proclaims that the resurrection happened in his letter to the Corinthians, though gives no source for this. It’s very much a “hey this is what I heard, what had happened was...”
The earliest of the gospels was written 20-30 years after Paul’s writings and were, at best, second hand accounts.
The point is that all the historical info we have about Jesus was recorded after there had been, at the very least, a couple decades worth of oral history and mythos generated about him by his followers.