i hate the word, leftovers.
it took me a long time to realise what people were talking about.
to me, and from my background, that word means what goes in the slop bucket.
scrapings off people's plates, so the idea of keeping using is repugnant.
we didn't have what people now mean by it. food was eaten, or if not, rarely, stored to be eaten.
it remained food. no need for another word, except eg the meat, potatoes etc.
i think it is a different approach, not just of words, but cultural, as is often the case with different terms. they are more fully understood in context.