They were chased by a literal god-devouring eldritch abomination known as Humbaba. Humans thought that the gods were wayward members of the mythical First Civilization and honored ancestors to the Imperial Family. The Gods admitted, they had no idea themselves, they were the children of refugee powers who had fled from the same entity in an on and off chase that had been going on over nearly the last million years.
There are throwbacks in two respects:
residual traits and actual throwbacks.
The residual traits are things like elves still possessing antler racks (indeed, care and grooming of this rack is a major part of elven culture and fashions) and also powerful elven elders can undergo a ritual that allows them to summon flora wings. Dwarves have much easier access in that they can integrate stones and metals easily over their flesh, this is used to basically 'staple' or stop up wounds, getting crazy with jewelry, or for basically only needing to do a combat roll through a pile of metal to come out fully armored for a fight.
Actual throwbacks are a handful who requested to the gods they would rather continue as they were and serve as guiding ancients for their people. So there are a few grass elks and rock lobsters
around, though they generally live in a bit of isolation, mostly the dwarven ones because... lava people.
As for what the gods were like? I'd say they're probably the most humble deities in fiction. They only reluctantly accepted being called gods, though they would be first to point out their knowledge was lacking and they served no integral function to support reality. They were powerful, knew much, and were grateful for humanity's aid to no end.
Such that when Humbaba descended upon the human world, the elven and dwarven gods swore mankind would not suffer for their error. The gods would finish the battle, once and for all.
*creator spoilers: yes, the gods were descendants of the First Civilization.