Perhaps I should revive a Reynardine thread to say this, but first I am persuaded by the theory that the narrative is an import about the early french brigand, and second I harbour an idea that its resonance to Victorian times lies in its possible reference to the budding of female sexuality. There was both in and before Victorian times a fear of the possibility that men have a largely fixed (and worsening) tumescence-detumescence time, whereas female sexuality may be insatiable: this couples to the fear of vagina dentata, the symbol of castration through sex, to which the "teeth" line (if it is not a contemprary addition) might allude.

IMHO the source of a folk song is the basis of its meaning, and it is well to know (say) that the tune we usually sing to the Lykewake Dirge is actually a Victorian neologism (as IMHO is the Prince Albert verse in "the Deserter" (aka "Radcliffe Highway")