Also Adam and Eve would have nothing to do with ancient history with regards to billions of years ago. He has Archangels, TWG, souls... Adam and Eve are part of that belief system, and their Choice led to the fall of humans. The Angel's theme throughout the series has been about Choice, and Harry is the central person of the stories which means his Choices are probably what will decide the fate of things. He's also a Starborn which seems to be of importance.
As far as we know, his magic can affect Outsiders, for an extent, so a Starborn would be integral to the war.
However, TWG and Archangels in DV seem to have two different roles. According to Dresden(a bit), Michael, Uriel and their bunch, He is capital G God. His Archangels can level galaxies. (Even though they can be scared to death if they're pet-named)
According to Basserina, and some other nasties/not so goodies, he is but one of many small g gods. He just gained the most influence, following, and thus power 2000 years ago, and all but drove the other gods to dust. Yet they still exist, and trying to regain some following.
There is also the fact that Hades doesn't have many believers anymore, and thus not many souls go to his dominion after they die, but those who do, he has the power to judge, and keep, for eternity. TWG has no power over that. Which makes me lean towards the "The most powerful of small-g's" theory. The attributed super powers are just PR.
Edit:
I'm getting the hang of the initialisms thing.