lol if they would ever come, it would be so weird we wouldn't be able to grasp it.. The natives in the New World also didn't see the Nina, Pinta and Santa Maria on the horizon..
The Shaman had to show them the way.
My idea; aliens are all around us. We are aliens. One of the atoms in the psychoactive mushroom is the most alien substance known to man.

Check The Pharmacratic Inquisition (warning three hrs, 65 mb)