One thing Stargate didn't have enough of, was truly alien aliens. The Milky Way Replicators were the closest thing. The Goa'uld were just appearing as people, the Ancients were probably humans from the future (because the identical evolution hypothesis makes no sense), the Nox were hippy Ancients and not seen much anyway. The Wraith might've been the most numerous alien organism, but apparently they were also a byproduct of a human-like species.
Potentially everyone except the Asgard and that anti-terraforming civilization were derived from life on Earth. Edit: Also one or two in Universe, who I wish had had more screen time.