The old adage says, "Those who can't sing, sing rock 'n' roll. Those who can't sing rock 'n' roll, sing rock 'n' roll anyway." You might as well substitute "folk" into that.

I think it's a lot of bunk that folk singers are supposed to be bad, and it's frequently an excuse for folksingers not to invest the effort in getting better. If you've got an amazing voice, it's a strength, not a weakness. Take your amazing voice to a music teacher who will teach you theory and practice, and learn the mechanics of music. Not all of us are natural whizzes at this and we need someone to help stuff it into our brains :)