>>526848021
Goku does say he's just a human early on, but at the time he was also being coy and not telling anyone else more about Uub, though, on the other hand he could have just vaguely replied with "more or less" when asked if Uub is really a human, but he just says Uub is a human.

Although, considering Uub's soul is what makes him so powerful, inheriting some powers from Buu, or at least, having a knack for learning magic isn't far fetched.