I think some are probably interdimensional but most are the fallen ones. I heard an interesting theory the other day about the UFO issue.
The classic greys and insect looking goomers are what the government is talking about. The theory notes they are becoming hostile, thus the disclosure to the public. These goomers at some point commence an invasion/take over of the planet and we are helpless to stop them.
Another group that has popped up time and again the nordics-fair haired, beautiful, humanoid looking aliens show up and save humanity from the greys and we allow the nordics to take over and we worship them as saviors. In reality they are the fallen angels. The great deceiver/anti-christ is in this bunch. They accelerate transhumanism and we give up our humanity and dominion of the earth to them. At that point they openly declare war upon the Creator/God.
It was an interesting theory that seems to align somewhat with scripture from the Bible.
That’s an interesting narrative.
From ancient times Mystery Religion initiates have been astral traveling into the abyss in the fallacious belief that the abyss is an astral heaven or for pagan Gnostics, the Pleroma. The abyss however, is the abode of evil spirits. It exists in an unseen dimension. Today DMT users are traveling there and report seeing and interacting with humanoid beings, Nordics, grays, insectoids, and other creepy beings.