Long long ago when I was in Highschool, Dinosaurs ruled the earth and I was not into cycling I learned about classic music. To many it seems to mean old respected music. This is not the case. There is lots of old respected music that is anything but classic. Classic really means simple (as without embellishment) and straightforward.
It is the same in cycling. A classic is a simple straightforward race. Barring fouls the first guy to cross the finish line wins. Simple, straightforward.
Of course the Major Classics is something different. That is what most of this thread has been about.