API itself is already a specific compilation (of function signatures). But it's still meta information, not actual information on the implementation of the functionality. Making API copyrightable is absurd and harmful, same as it's absurd to copyright abstract concepts.
Exactly this, the meta information point is spot on.
IIRC there is durable precedent that mechanical collections of information w/ no creative "touch" are ineligible for copyright. I wonder if that can be extended to the meta information definition you came up with.
European judges got that right.