We have WOJ the Greco- Roman pantheon held the Gates before the Fae and that elements of that pantheon poured power into the Mantles of the Winter Court, Harry’s guess as to the mothers names indicates that.
We also have a WOJ that his wrestling book involves much of that pantheon are pro-wrestlers suggesting they accepted the power down option and are tapping the adulation of their fans to maintain that power. I suspect many wanted ‘out’ like Mac from the perpetual conflict.
All the original gods, angels and Titans existed before linear time, the White God created linear time for humanity to evolve, and in doing so expelled the Outsiders, I suspect because the White God is a version of the singularity, and will only come into existence when humanity, and its technology reach a certain point which has yet to happen, but will in the BAT. When created the White God is not bound by linear time but still has to close the circle and the Outsiders want to disrupt that destrying the Outer Gates. The Fallen on the other hand want their version of the White God created, hence the Fall. The Fallen and the Outsiders therefore have their own agendas which occasionally intercept this is why Nicky thinks he is a saint, he is trying to bring about the Fallen version of the White God, with Lucifer as the core of that entity and why he fears Fallen cooperation with Outsiders which is where Cowl comes in, who has his own agenda as Master of the Future, perhaps his own version of the White God with him as the core of that entity.
The creation of the Denarians and in response the Swords were the opening gambit in the battle by the Fallen for control of the White God, we are in the endgame as Listen indicates with the control of the White God being decided by the Starborn/Destroyer i.e. Harry. Harry is not going to be the core entity of the White God though. I think that will be either Uriel or Michael (although the latter is good candidate for taking up the Kringle Mantle when Odin dies in the BAT/Ragnarok) Harry is John the Baptist to the White God. He could become the White God, because the White God is an Intellectus, and Harry is an unreliable narrator and makes mistakes in the narrative.