The problem is that we all experience the past. While I didn't experience the Roman past, I do experience the past through which I lived. Hence, I find it natural that there was a past before me.

Additionally, why would the past, as an experience, be the same (relatively) to all of us? Why would we all naturally experience the past?

If they did make up the past, I have some serious questions about the detail they put into making up the life of this Peele fellow I researched while earning my master's. He had something like 25 boxes in my university's archives, most of which was random letters he either wrote of received over the course of his entire adult life. I would have preferred if they had made up maybe 1/5 of a life, at least for someone that nobody outside of my school had heard of. Hell, I didn't come close to finishing looking through his material, and I'm probably the only person that ever will (he donated a major collection to the school, so we keep his materials with it).