Ok, the problem here is that once again it seems like we are pigeonholing "folk" music. It's like asking where did drama come from.I think first you have to define folk. (Boy, that ought to stir up a hornets nest!) Then you can figure out who first sang it.
Minstral and Bard are pretty loose terms as well. What makes a bard? Folk music? Or is it folk if a bard sings it?
Don't hurt me.*g*