"...a creative writer" is surely exactly the kind of writer he was. Someone who uses their writing abilities to sub-create a world.

Yeah, and I know that the kind of people who get jobs teaching "creative writing" might use the term to mean something very different, probably something to do with using language in ways it hasn't being used previously.

Tolkien wasn't a novelist; border ballads aren't lyric poetry; Jane Austen didn't write stream of consciousness. They are all examples of language being used to do certain things superbly.

And the same kind of thing is true about film, and Peter Jackson achieved something quite remarkable in these films.