Wriitten and spoken English are grammatically different. Illiterate people would hear the former second-hand - in England maybe mainly from the King James bible and the prayer books.

People who don’t read or write much often write in an awkward style because they are more used to spoken English.

Is there anything gramatically distinctive about songs thought to have started in an oral tradition? I wonder if Jim’s Traveller songwriters wrote in their vernacular style or in something different.

It is fairly common for kids to have one form of English (or Scots etc) for the playground and another more standard version for the classroom.

Maybe the songs written by the common folk that persisted were written by common folk who were more skilled with language than their peers.

Can we tell anything from the style of language?