If YOU hadn't come up with the core idea, I never would have gotten to run with it. Don't sell yourself short.
Fleshing things out for nonhumans:
Dwarves: enslaved to your version of the Goa'uld.
Warforged: I'd use my Inheritor idea, making them Psionic dwarves in fine dwarf-crafted bodies, kind of like Daleks or Cybermen. Suitable dwarves are forced to undergo a surgical procedure placing their brains in to poweful mechanical bodies buy their masters... As such, they fill the role of The Jaffa.
Bonus, like the original Cybermen, the Inheritors also have a weakness for gold, albeit a moral failing, not a physical one.
Gnomes: make them true Fey and use them as your version of the Nox.
Elves: pick a race, maybe two, make 'em the civilized kind. Don't need a bunch of treehuggers in space; have them be masters of bioengineering & biomagitech.
Neogi, Illithids, Beholders or Aboleths: any of these could be used as Goa'ulds or other nasty, powerful races.
Half-Giants or Goliaths could be heavyworlders.
Thri-Kreen: got nothing right now beyond what is in the books.
Halflings: they might be fun as stand-ins for Asgardians.
Beyond that:
I love the use of creatures already written up in other D20 game books. Seshayans from the D20 version of Alternity are awesome for a decadent, fallen race. There's also the Tarn Idoun, a silicon-based race from DragonStar that are kind of living IOUN stones...with a better write up than the shardminds.