I’m in my 40s and only heard “We Shall Overcome” last year. For at least 30 years I’d been aware of it’s existence, know of it’s importance, known the circumstances of many famous performances, known many of the lyrics from having seen them written out. However I’d never actually heard it except for a couple seconds here and there. I finally heard it performed last year.
I mentioned this at the time on some forum (can’t remember if it was SD) and many people had the same experience as I did.