Lavender Outlaw
I think there are other lifeforms out there somewhere, but I find it highly unlikely that they have visited Earth in recorded history.
I'm surprised that no one has mentioned
sleep paralysis. This, or something similar, could explain quite a few abduction stories.
There are plenty of interesting "clues" throughout history to suggest some sort of extraterrestrial intervention. I direct you to the History channel's series "Ancient Aliens" for various examples.
This doesn't mean that everything they discuss is undeniable proof, but you have to admit, it brings up quite a bit of unanswered questions and opens the doors to many of such possibilities. There is so much that we still don't know even about our own past/history/origins that leave this for a LOT of debate that we can't quite account for. The possibilities are endless! XD
So, your "highly unlikely that they visited in recorded history" maybe it was recorded and we just don't know how to piece it together. Alternatively, as conspiracy theorists would surely agree, there could have been government cover-ups for said "recorded history" that we could be unaware of.
There are so many variables and so few facts to grasp at.