More can always be said on the matter, of course, so if anyone would like to address the matter of pre-modern views on the shape of the world, please go right ahead! Our evidence is largely fragmentary, but what we do have certainly does not indicate a 'commonly accepted' view of a flat Earth. u/jschooltiger examines the matter here, and also in the context of timezones; also u/qed1 in this post, and u/sunagainstgold on just how accepted references to a round Earth was.