It takes a LOT of dedication to study an idiom or style so intricately that you can replicate it. It takes a lot of understanding of music in general, and what you want to replicate even more. There’s an art form to that that should not be dismissed.
Yes, but that is a more technical part and just makes you a plain epigone not adding anything yourself.
In terms of film scores it has also to fit the movie. “Originality” above everything may not be necessary to do so by itself.
For me, “originality” doesn’t mean that every single aspect of any piece of art has to be “original”.
Technically no art is totally free from what came before (that “standing on the shoulders of giants” saying some copyright illiterate like to use as an excuse often). Maybe a better term would be “personal originality”. Just like you can (often) identifiy Goldsmith although you find Stravinsky, Bartok and whatnot styles all over the place for example.