they are very simply former humans who have escaped the cycle of physical incarnation but in the wrong way.
they are attracted to malice, anguish, overwhelming guilt, trauma, and general toxicity. like they were in their human lives. over and over again.
they're a spiritual and spatial phenomenon that involves negative and malevolent energies, intents and actions that linger in spaces, outside of time and they manifest in places where they feel attracted to these energies and are further stabilized by fear, especially.
you can find them en masse at the sites of fatal wrecks, murders, rapes, in structures that involve familial trauma, toxic households that contain narcissistic, socio or psychopathic behavior, and in the midst of those who suffer from depression and exisential fear. especially of mortality or just general malaise about life and the world we're incarnated into at this present moment.
indigenous people will tell you that the only evil in the world is produced from the foul hearts and spirits of oppressive and malicious men.
sometimes they turn their victims into monsters as they're trying to defeat a monster.
the universe doesn't produce purely malevolent and inflammatory lifeforms and i don't understand the notion of why an interdimensional being would be so malicious as to behave in the way that these entities do.
the truth about them is rather dark but to believe that these are aliens or higher beings that are here to observe us and stoke our fear and paranoia and misery is just too much.
you, however, are of course encouraged to think whatever you want. this is just the opinion that you asked for and the source is that i live my life as a practicing medicine man of a First Nations tride for many years - raised and taught by my elders of my flesh and blood that both brought me in to this world and brought me up. i have mingled with Shadow People personally and they are neither demon nor alien.
they are simply wayward souls. intoxicated with fear and suffering.