Tolkien actually revamped thatso many times, and never settled on where they came from. Just that Melkor used some existing race to make them, since he couldn't make life from nothing, which was what he envied most about Eru.
Hehe, but he is! An earlier comic of mine (which isn't in vector form yet but should be) has him playing the one-man band as the rest of the Valar sing with Iluvatar... He always kind of struck me as a Middle-Earth Dennis the Menace.