Nothing rings the bell about the Great Fire but by the name must have something to do with Ra.
As well the Massacre. The Massacre looks like very much the mith where Ra got enraged by humanity arrogance and misbehavior and commanded his child HATHOR to punish them as SEKMET which made a bloodbath almost killing all humans and was only stoped by Ra because themselves thought she exaggerated.
By arrogance it's must have been their knowledge here the reason they got massacred.
And good piece of clue for unknown god!! If he doesn't met their ancestor we can excludes Zeus :cccc He still could be Jesus by that but I still find it ridiculous.. haha (cuz his persona......) so we can only move to mesopotamia! Yes guys he's my initial guess my dear Gilgamesh yeah
He could be Gilgamesh, but according to Mesopotamian mythology, he was only demi-god. He was really strong though. But we know that Horus (also a demi-god) would not be able to beat FG in fight 1v1. So I don't think that as a demi-god, FG would be this strong (what im trying to say is that if hes THAT strong he would probably be a fully fledged god, not a demi-god). But then again his journey to Egypt could be tied to the fact, that Gilgamesh spent lot of the time searching for a way to make Enkidu immortal. Sooo who knows
Wow life with Itto must have made her this way