“How do we know that WE are not the “aliens?””
Because there are animals existant today -— with whom we share great genetic similarlity -— that are clearly present in the fossil record.
If we are “aliens” we came at a single-cell level.
Squatters rights after the first billion years.
We KNOW that? Or do we just “assume” that?
Did we come here in one piece? Did we evolve? Were we created?
(But don’t get me started!!)