A folksong probably WAS written by one person who may have been the original singer. But it was kept alive by the fact that it was a subject that "spoke" to other singers and the tune was something that other people would walk away humming. If the song didn't do either, it never lived long enough to be a "folk" song.

There's plenty of singer-songwriter sh--, I mean, cr--, I mean, oh, STUFF out there that is going to die with the writer because nobody else can perform it.

Bat Goddess