What's a classic, then?
A classic is a work that remains interesting - necessary - on many levels and in various dimensions of society. That is, valuable to both young lovers & old scholars.
Classic (the adjective) does not by any means equate to famous, successful, traditional, formal, classical, classy, etc.
It does, however, have connotations of original or ground-breaking. Because a classic is - somehow - both inimitable and foundational. It sets the pattern or template for something new which becomes perennial. A true invention.