Why must “they” be aliens?
Instead of beings from some distant planet, why not consider the possibility that future earthlings have mastered time travel?
How could time travel be possible?
I will explain that when someone explains how travel over zillions of miles would be accomplished.
They are part and parcel of the same coin...............
That is the beauty of this topic. It can be a lot of things, or nothing. It is entertaining but mostly useless.