"... the API is just a functional (non-creative) description of the correct way to interact with the code."
Google argues that all the design work that people put into figuring out the best APIs for their systems cannot be protected by copyright. That all that design activity is "not creative," in your words, basically worthless and not worthy of legal protection. I really have no clue how this became the predominant belief amongst software people. Convenience? Stealing someone else's API design is easier than figuring one out yourself, I guess.
Look at the design of the C++ language and its standard library. Think about the huge amounts of effort that Bjarne Stroustrup (and others) put into making the language and all of its API pieces fit together in the best way in their view. Now, imagine that he instead did all that design work only for his own company's use and never intended it for general consumption or use outside his company.
The arguments put forward by Google, and many others, are that if all those complicated, interconnected APIs somehow leaked out onto the internet (e.g. - a disgruntled employee surreptitiously posted them somewhere without permission), then everyone else would be legally free to copy them verbatim and reimplement the backing code without a single bit of permission nor consideration going back to Bjarne nor his company. They are APIs that aren't copyrightable and almost surely not subject to patent protection. Google's approach values all that API design work as entirely worthless and not intellectual property in the least.
That's ridiculous. API design is a HUGE part of software design and development. I'd argue that it is often more important and valuable than any particular backing implementation of the API.
Ok, now imagine a bit different C++ scenario. Stroustrup really likes his C++ language and wants to publish about it, including his specific API design. Does the mere fact that he voluntarily revealed his API to the public (without any license but with a copyright claim), now allow everyone to run off and copy it verbatim again without permission nor consideration back to him? Again, that does seem to be Google's argument and it seems bonkers to me.
Arguing, as the EFF does, that open and free APIs are a good thing that facilitate competition, wide adoption, superior implementations, etc. is one thing. But arguing that all APIs are inherently open and cannot be protected as intellectual property -- that anyone can legally come along and copy verbatim the huge, complicated class hierarchy and interfaces that you designed for your software without your permission nor consideration -- is an entirely different proposition. Authors should absolutely retain the intellectual property rights to their specific APIs. They can license them or put them in the public domain as they see fit.
Now, the obvious criticism of my stance is that what is to prevent someone from putting and enforcing a copyright on something absurdly simple like C's strlen() function or something similar? Would we have the equivalent of patent trolls trying to extract money from anyone who codes? My answer to that is it would be up to the US Copyright Office and the courts to determine what is fair-use and what is simply too trivial to copyright. For example, a book author's copyright does not give them the right to go and sue anyone who happens to use a sentence that happens to appear in their book, but it does allow them to sue people who reproduce significant sections of their book that go beyond fair-use.