So there must be a connection to France, either to Brittany or (more likely) to the whole nation. This of course does not mean that the song is from France or dates back "centuries". As we know, songs can easily be "tossed together" from known motifs. Judging from the style only, I'd be very surprised if it were any older than 19th century. (For example, the boy's age being considered important.)

I don't see the relation to "Ave Maris Stella" either, not even to typically Catholic ideas. Raising a family to defeat Satan sounds Calvinist to me, whereas the abbés, if they were the only authors, should mention celibacy as even more effective.