[soneca]

No, it was not. Well, kind of depends of what you mean by “back then”. But the term classical music is not a modern creation talking about old music.

The term was created while people were creating this genre of music. Classical originally was meant to refer to things from Antique Rome. But, unlike other art forms, like literature and sculpture, no music from Antique Rome survived, no one knew how it sounded.

This kind of created the opportunity to redefine what “classical” meant in music, so a few people decide, centuries ago, that this genre of music would be called “classical” at that time already, not now.

https://en.m.wikipedia.org/wiki/Classical_music