I think these questions are better left unanswered because they would be very difficult to explain in an understandable way>Who built the train?
does it matter? the train can continue to run without necessarily having a creator like a god or supernatural force>Why did they build it?
to help people, that is more than clear>Where is the train?>Where is it going?
does it matter? the train could perfectly be on a planet, virtual reality or parallel dimension and it would work exactly the same>Why even a train, why not just a long building?
because is the infinite train? would you prefer a series called the infinite building?>How old is the train?
It is the only thing that would seem to me in need of an explanation, Jesse and Tulip are surprised to be on the train and if it has always existed I doubt that there is not at least one class on it in the humanities subject.
But in general I think it's better to just think the same as Perry, I mean it seems that he doesn't even know how his powers work