It has been argued that there are only ten basic plots in stories. (Please don't try to pin me down to the exact number (six, nine or whatever). In which case there can be only a limited number of roles that characters can play in these stories. So you will be able to translate these roles into "archetypes".

I've just been reading Terry Pratchet and Jacqueline Simpson on Folklore, wherein is said that a witch (and, by implication) a woman, falls into three categories: maid, mother and crone. (Baby/child being excluded.) I think whore has been overlooked there....

I recall a critique of R A Heinlein's fiction, in which it was convincingly argued that every one of his characters was based on three stages of growth: young, inexperienced and naive; mature and competent problem solver; all-knowing guru philosophiser.

The seven ages of man is as another, more familiar, example. These demonstrate that we can all be simplified and codified, by deletion of our individuality and selection of key duties/positions.

A folk song is necessarily limited in what it can provide in the way of character differentiation and/or growth. If novels have problems with generalisation of characters into simpler roles how much more problem is there in a song? The girl with the nut-brown hair. The dark-eyed girl. Bonnie Suzie. (OK, a traditional ballad has longer space, but the format does not permit character development: people have roles, around which the events occur.)

Now if you want to proceed to build mountains of discussion around the basic fact that characters in songs must play a limited number of roles, with little or no differentiation, then by all means do so, but I argue that it is no more than the limitations of the form.