So, to be in the folk idiom a song must meet the following criteria :-

1. word dominated, narrative communications of ideas and emotions
2. accompaniment, where it occurs is secondary to the narrative
3. The characters in the songs are identifiable people, usually with occupations and individuality
4. They have problems and situations we can all identify with
5. Structurally they ar four or eight line versified, they may have choruses but they hardly ever repeat phrases other than as a plot device
6. Performed in a traditional "fo!ky" style

No mention as yet of the melody.

Is this correct? If not, what have I got wrong?

Sorry to keep labouring this but I do want to make sure I fully understand what you believe to be in the folk idiom before I respond.