Some good replies here.
To the question of originality versus creativity, it does indeed come down to looking at the whole or it's parts, as Delock said above. One thing I would add is that from both perspectives, not only is it important to remember that originality or creativity is possible (respectively), but this originality or creativity can still be significantly new. If you want proof of this, take a look at the impact of people like Marx, Freud, and Darwin. One can say that these ideas were wholly new in the very fact that each thinker introduced terminology and language that made it possible to think these ideas - that the idea of evolution (for example) meant something very different before Darwin, and that the latter original idea resembles the prior idea little more than in name. Or one can also say that these ideas were displays of creative arrangements, aspects of which had been present for centuries. But either way you look at it, as original ideas or creative arrangements, one cannot deny the impact of these thinker's ideas. In short; don't underestimate the new any less than the potential for the new, there are indeed new things under the sun, and some of them are pretty big deals.
edit: in regards to writing, the advice for each perspective (whole or parts) is the same - keep working and keep trying. If you see things as original in themselves, keep creating, keep daydreaming, keep imagining, and keep building up your own ideas. If you see new things as a conglomeration of the elements of other stuff, then read, research, experiment, and keep trying at it. I've found that the best way to prove that novelty does exist in this world is to go ahead and make some for ones self.