Can you copyright Harry Potter the character? Or can anyone use recognizable Harry Potter reproductions in commercial context, be it alternative books, movies or merchandise?
Now, the question is, where do we draw the line: As per Oracle, there cannot be any other character that does what Harry Potter does.
You specifically need to argue that the API itself - the specific combination of types in a specific order, with a given set of Unicode or ASCII characters to identify it - is not copyrightable, not just that it's made up of uncopyrightable things. This is harder, because this same practice in other contexts (e.g. music, literature, and so on) is very much protectable. You need to argue that software is different.
The description and name matter a lot for this, and are typically quite general.