Interesting thoughts. Though with bits minor corrections:
So the MC being able to use sorcery means he is descendent from the mother
Minor thing, but that wouldn't track. None of the Firstborns are sorcs. And they're direct children of both Horney and The Mother. Sorcerers are either The Mother's Chosen or their descendants.
so basically the MC is the human god!
as the demon god explained all other "gods" are just demi gods or ascendents
Firstborns aren't either. And they're supposedly full-blooded gods.
but there are only 1 god per race so i supose old horny conjectured everything
Not really true. The Demons have 4. No reason Humanity can't have 2. Or 3, for that matter *nudge**nudge* *wink**wink*
i also suspect the others are connected to the mother somehow!
they only started appearing and taking out pantheons when the mother disapeared
No. The Outsiders have been terrorizing Humanity ever since before The Ascension. So, roughly 12k years ago. Mother only disappeared ~1800 years ago.
its also quite interesting that they only target decadent human pantheons!
They tried to target The Fae twice and Horney (despite being barely his younger self now), Cu, and Lugh are far from decadent. It's only Thor that believes that and nobody else.
its also quite interesting that there is only 1 god per race and yet the humans had a couple as gods...
No. Demons have 4. Humanity had 2. Schwartzalf seem to only have 1. There doesn't seem to be a hard limit to these things.
was that why humans were so fragile at the start ?
A couple of things, but mostly I'll attribute it to having no magic. One thing to remember: Samael is talking about things tens or hundreds of thousands years ago. And people from back then simply would have no chance against a mage. Nevermind demon hordes of them. As such, they became sport to hunt like we do the bunnies in the woods. Only after humanity's sentience gave birth to both Horney and The Mother that magic started to enter the Human race. Youngest estimate of Horney age is ~50k years old. And he likely is way older than that.
she disappeared when the war was piratically won!
While we have zero concrete knowledge about why and how she disappeared, but it does seem to be that she tried something. Whether that was a success, failure, or even still being played out is anyone's guess.
MC being fully god along with Horney and The Mother though does seem like a great idea. The two of them were born from Humanity and right now the same Humanity is propping up MC for his destiny. Not exactly 1:1, but I can totally see it happening. Actually, I want to see it happen. Though I'll also take whatever Droid has planned for him.