My introduction to ballads was Nic Jones singing Annan Water via a Dansette record player. But Annan Water as by Nic or as writ on the walls of the Blue Bell (or Ball?) in Annan both start in the 1st person as border and bothy ballads already mentioned yet must be ballads.
The parameter that the song should contain no comment I hadn't thought of but as I'd never thought of 'Eggs and Marrowbones' or 'The Molecatcher' as ballads perhaps I'd assimilated that feeling without identifying it. 'John Barleycorn' tells a story but because it is clearly a fictitious analogy it doesn't feel like a ballad any more than (for me) Marrowbones or Molecatcher. Perhaps the story has to feel as though it did once happen? But then there's my favourite Tamlane. Tricky. What about scale - fair enough the dread of 42 verses but can just 3 ever be a ballad?

John, I love ballads me.