That’s very British. Heads and wells and strange old men.
From what I remember Jacobs was a collector of folktales. There’s usually a bit of tweaking (sometimes significant) in retelling the tales. But its less adaptation than recording oral tales. So you’ll never really know what changes were made unless others collected other versions from nearby. Or like the Grimms Jacobs kept records of the unvarnished stories as told, and where/from whom he collected them.
He seems to have been an Anthropologist so I’d imagine that’s around somewhere. But the morality play aspect of a lot of these things is often what’s been added around that time. The earlier versions of a lot of your famous fairy tells are a lot stranger, and lot more ambiguous
It’s worth remembering that the Romans were an invading force and the only source of info on the ancient Celts.They painted their neighbors as baby killers to justify themselves so I have no doubt they did the same with the Celts.
