Phanes
Phanes/heavenly principles/first descender.
Is the spaceship the twins came in, you can get the loredump from their new skins.
It talks about a being that traveled countless stars searching for a home for civilization, that the first to be born were twins and that turning an entire planet into a suitable ecosystem was nothing for it, that even altering a star was not much.
That it deactivated its "idea association module" basically its Emotional intelligence.
Phanes is basically a pioneer of mankind using the genetic info he has to try to bring human life into Teyvat.
It's traumatized from all the worlds it saw perish and has become a coldblooded machine who only thinks rationally.
Thats about it.
The sky is fake and all "tears" tend to look like some kind of deformed cubic shapes.
All kinda glitchy.
With what we know about Teyvat, the abyss, the fake sky, the upside down tree??
It could even be safe to assume that Phanes arrived, but while he was bringing life the planet collapsed and it had to create "Teyvat", which I also think it's viable to say could be a sort of "safe area" or "bunker".
Do you know how civilizations fall?? On their own weight, searching more.
That's why Phanes keeps them locked and tight, since it can't think emotionally due to the IAM being deactivated it think it's better to keep them closed up from going forward too much.