The Timeline

Hoet's Breath of Life:
Gods created world, world was entirely immortal, and like a paradise.

Old Ones arrive on the plane, and are also immortal. Old ones have a bad effect and influence on the world. Which the gods didn’t like, so the gods make the world and everything on it mortal.

No one knows how they arrived, and where they come from, but they understand that Hoet was a juicy target (land of immortality)

Old ones aren’t necessarily evil, they just influence and change things [Seven old ones?] e.g. Sins, Wrathful, Lustful. (Maybe an 8th)

Evil Gods were created from the Old Ones - Old ones absorbed them, influenced them and created an evil version of them. The rest of the Gods escape away.

The gods stay away from the material plane as much as possible, incase they arrive and become mortal themselves.

Mindflayers serve some form of Old One? (If not one type per old one.)

Old ones were either expelled or came here by choice - regardless, they brought part of their “world” with them. These pieces are cyclopian, strange geometry, eldritch ruins, big towers. Large underground complexes. [These ruins are covered up by gods, or purged by gods? Quests given to them from the Church.][If this isn’t dealt with correctly, or fast enough the gods itself will deal with them with heavenly purges - Angels]

Events so Far:
In order:

Gods create world.

The arrival of Old Ones, and the converting of some gods into Evil Gods / influence of sinful ways.

Gods band together, remove immortality. Begin abstaining from material plane.

Evil gods create second celestial realm for themselves.

Some kind of terrible Ottarim event, causes the union of the 3 races/groups into the imperium.

First Queen rises to power through imperium.

A (old one) ruin is found, and there is a large battle between angels or old ones across it. This is recorded.

[These events will be within 100 years of present day.] 

War between Ottarim/Imperium beginning to rise. Imperium winning due to strength of Sylph/Fey magic.

Ring is found that affects the (Current) Queen (Fey/Sylph)

Queen enters coma. War is much more even yet still raging.

Party enters somewhere on the main continent.