1610s, "of or belonging to the highest class; approved as a model," from French classique (17c.), from Latin classicus "relating to the (highest) classes of the Roman people," hence, "superior," from classis (see class (n.)). Originally in English, "of the first class;" meaning "belonging to or characteristic of standard authors of Greek and Roman antiquity" is attested from 1620s.
<a href="https://www.etymonline.com/word/classics">Etymology of classics by etymonline</a>
Harper, D. (n.d.). Etymology of classics. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/classics