I think the most compelling reference work right now is probably a collage.

> a piece of art made by sticking various different materials such as photographs and pieces of paper or fabric on to a backing.

And the law there is actually pretty nuanced and tangled: A collage, while not a compilation, may be a collective or a derivative work. A collective work has copyright protection, but a derivative work does not.

So basically, given the current environment I think we're honing in on a super clear and very helpful "sometimes"...