I don see why having language makes you a superior species.
Language gives us the ability to utilize knowledge well beyond each individual's personal experience in both time and space.
And being a sperm whale gives you the ability to dive three kilometers below the ocean unaided and devour giant squid. Are they superior to humans because they can do that and we can't?
If I took the libertarian POV in which individual self-sufficiency is all that matters, then I would admit that they are. However despite the fact that libertarians despise the fact, man is a social animal. Language is the glue that binds us together and enabled us to go even deeper than the sperm whales and to acquire giant squid for ourselves to devour if we wish, so if sperm whales are superior, it's not because of that. That's the problem with libertarianism. It totally ignores how functional human societies work.