You're missing an argument in there that joins your two assertions.

The fact that something is creative or requires skill to produce doesn't mean that it should be copyrighted.

Copyright is a government enforced monopoly. In order for society to enforce that monopoly on behalf of private enterprise, there has to be a quid pro quo. The usual one is to promote creation and distribution of new works.

The question then is: would no APIs exist if they weren't copyrightable?