[still locked etc.]
People from different times are brought here. You must be from our time, but just a little earlier. Before you died, I mean.
I have met people from forty thousand years in the future here. And sure, they could be lying, but why would they be? What is the motivation to lie to some kid about that kind of thing? Especially a consistent lie with very specific details.
We are being jailed by a being that disapproves of our actions, and has brought us here so that we can no longer commit crimes. Our fellow inmates have a very wide range of crimes, ranging from very petty to massively genocidal.