I'm inclined to believe that the difference that makes the upper bound of human writing (or creativity) higher than that of an LLM comes from having experiences in the real world. When someone is "inspired" by others' work or is otherwise deriving ideas from them, they inevitably and unavoidably insert their own biases and experiences into their own work, i.e. they also derive from real-world processes. An LLM, however, is derived directly and entirely from others' work, and cannot be influenced by the real world, only a projection of it.

> Would you rather have the novel that the LLM generated (the output), or the prompts and process that lead to that novel?

The "process", in many cases, is not necessarily preferable to the novel. Because an important part of the creative process is real-world experiences (as described above), and the real world is often unpleasant, hard, and complex, I'd often prefer a novel over the source material. Reading Animal Farm is much less unpleasant than being caught in the Spanish Civil War, for example.