I've often wondered if people back then were more skilled at music and art overall since there were fewer mindless leisure activities.
But, at the same time, I'm sure a guitar or ink and paper were comparatively expensive, so who knows.
Plus people could drink at 10 back then, so I'm sure they found plenty of mindless distraction.
Guitars as we know them are actually quite new, and going by "350 years" in the article, didn't really exist when these bits of paper were dropped through the floorboards.
Vermeer's The guitar player dates back to just over 350 years ago, shows a baroque guitar, and as far as I am aware these were complex, really expensive things.
https://www.youtube.com/watch?v=9o-TOg-y_BI
I would guess there were lots of lutes and gitterns, though; they are relatively less complex. And I would absolutely think that the children who went to this school saw, owned and were expected to play musical instruments; they came from those sorts of families.