This question seems to assume that the Romans actually used et cetera as we do. But did they really? By that, I mean: did they use et cetera at the end of a clause or phrase, without any noun agreeing with cetera, to mean "and so on, und so weiter, enzovoorts"?
If the Romans did not "invent" it, do we then have any idea when it began to be used in the modern way? I know it exists at least in Dutch, English, and French, but those could be borrowings from humanist Latin, for all I know.