Reading through the posts here it would appear that standards mean different things to different people. The jazzers have their standards compiled through constant usage and the rockers are starting to build up their own canon. Indeed, among the various efforts to come up with a definitive definition of jazz I’d sidestep the desperate attempts to nail the ‘improvisation’ thing but rather settle on ‘ a group of musicians playing a repertoire of tunes that are generally regarded as jazz tunes’ or something like that.
Looking through the Great American Songbook there are plenty of tunes I’d hate to have to play on a jazz gig. As there are several jazz standards that aren’t on the list at all, eg the bebop, modal, etc stuff, most of which doesn’t have lyrics as does the GAS.
Just my take.