I agree with the other comments here - you should be able to recognize the different renditions as such with an untrained ear.

Basically I’d start with knowing the notes of the song… kinda the most important thing but we just just don’t for this

I’ll note here too that the article is what draws that line (known vs unknown) not me - I’m just disagreeing with where they have drawn the line since there are older songs that we… “know equally little about”