From a Biblical perspective that is the only explanation. Unless one believes they are natural phenomena, which is not plausible. The idea that they are secret government tech is also not believable.
Agreed. Accounts of these "encounters" are much too frequent, much too spread out (all over the world), have gone on for much too long, and are much too complex...to be secret government tech or a combination government/civilian conditioning program.
I believe in the possibility of there being other creations in the universe.
But I also believe that our planet is in quarantine until the sin issue is fully concluded.