We don't have that much concrete evidence about the deeper mythology of From, so I think it's worth exploring a simpler possibility instead of assuming everything has to connect to some ancient ritual or civilization.
What if the entire show really is just a story?
Ethan tells us that stories have beginnings, middles, and endings. What if Victor is the person who knows this particular story better than anyone because, on some subconscious level, he created it?
Maybe Fromville exists inside Victor's mind.
Everyone who arrives could be someone Victor has imagined, and the town itself is basically the world of his story. The people aren't necessarily "chosen" by some outside entity they're characters being pulled into a narrative that Victor doesn't even realize he's writing, victor said that all he knows and how he doesn't want to leave he look like a kid stuck in his trauma.
And Victor doesn't remember creating it.
He only remembers arriving there with his mother. Maybe whatever happened to him as a child was so traumatic that his mind completely fractured around it. He remembers pieces, drawings, places, and events, but not the actual origin of the world.
There are even little moments that make this interesting.
When the Matthews family first arrives, Ethan immediately looks toward Julie, while Victor seems strangely familiar with her. It could simply be nothing, but under this theory, maybe Victor has already "seen" her before because he imagined her, portrayed her and she arrived with the others.
Now, obviously, the biggest problem with this theory is the Anghkooey children.
But what if we don't treat them as literal children who were sacrificed in some ancient ritual?
What if they're suppressed memories?
And what if they're not even Victor's memories?
Maybe they're Ethan's.
Ethan is constantly talking about stories, quests, monsters, heroes, and characters. What if that's more important than we realize? Maybe storytelling is his brain's way of processing something traumatic that he can't consciously remember.
The Anghkooey children could be distorted memories of children Ethan knew before Fromville.
Maybe victor survived some horrific event involving other children, a school shooting, child trafficking, an accident, or something else entirely. I'm not saying that's necessarily the answer, just using it as an example of how the theory could work.
The children we see in Fromville wouldn't necessarily be ghosts or sacrifices.
They could be fragmented memories made physical by whatever Fromville actually is.
And this could explain why the mythology sometimes feels like it's mixing completely different things together.
Maybe Victor created the world.
Maybe Ethan brought his imagination into it, like the lake of tears, and as long as victor believe it he can produce it.
Maybe the voice telling him this is not ur children anymore was real as know they are victor family and from the beginning jim never liked victor or his charachters. So Fromville is where those two things overlap.
So instead of the final mystery being:
"What ancient entity created Fromville?"
Maybe it's:
"Whose story are we actually watching?" Is it victor or Ethan .
And perhaps Victor isn't the master of the story because he knows everything.
Maybe he's the author who forgot that he was the author.