I wasn’t able to track down the 19th century book that inspired this post, but I suspect the book itself was the work of a theosophist (perhaps intentionally) over-applying the hindu concept of yugas and turning it into something more like Western concepts of magic. Whatever, I’ll just lay out some of the things that are on my mind:
In that book, it was asserted that there is a Middle Eastern concept of cyclical creation and destruction (there isn’t as far as I can tell) wherein man’s world is god’s seventh iteration of the idea (maybe more, maybe less? don’t remember). Holdovers from previous versions of creation include djinni, who iirc were kinda sassy about the situation.
In the TTRPG Feng Shui, which is similarly Orientalist but in a 1980s ninja ultimate power sense, there were sites in the world with cool mystical power, and whatever faction grabs the most of them gains some control over reality. The previous owners of reality can skulk off to a netherworld outside of time to scheme a return to power. So, like the djinni aforementioned, these guys are misfit leftovers from an earlier version of reality.
In the TTRPG Kult, something like judaeo-christian cosmology is sort-of true, but much nastier. God, there called The Demiurge, has vanished into a hole, leaving his Archons in charge of maintaining humanity’s prison – an illusory reality called Elysium which prevents us from realizing our godhood. There’s a lot more to the game that I won’t get into here, but central is the idea humans used to be god-like beings, running reality from an ur-city called Metropolis. In that capacity, we were nasty ourselves, conquering other races and destroying their worlds. The leftovers of those realities ended up – again – in some kind of netherworld slowly crumbling into an engine of oblivion called Achlys. Reality leftovers.
It’s just an interesting idea to me – people who don’t belong in the world, persisting, watching other people prosper in their stead. Envious? Miserable? Free, in a sense, but dying out. Can you think of more examples?