What's interesting is that you have some claiming "demons" and others that aliens are "extraterrestials". Why can't both be right?
What can be confirmed is that there are reports across history of things that can't be explained: Columbus recorded a sighting in 1492, in Nuremberg they described an aerial battle in 1591, plus there are various religous texts and examples of religions and cultures knowing about things that really shouldn't have been known about.
So is it really an either/or, demon or extraterrestrial, or could it be both? History has lots of evidence pointing to there being something. The question is why is the truth of that something so consistently hidden across governments across the globe?
If there are real space aliens, then it will provide a very different narrative of history than the one currently accepted.
I have a lot speculative ideas.
Uppermost is that historically alien being spottings tend to coincide with massive technological change.