Why do we take as the default hypothesis that language is, as you seem to be implying, a monolithic "thing"?
A more plausible hypothesis seems to me to be that language itself is constituted by a suite of cultural tools/skills. A language with a very limited vocabulary (especially one restricted to largely unhelpful words, e.g. "Justin Bieber", or "toe wart") is much weaker than one that has benefited from decades of cultural and generational digestion and iteration (i.e., a language that includes concepts like "however", or "on the condition that", or "art", or "gravity").
A more plausible hypothesis seems to me to be that language itself is constituted by a suite of cultural tools/skills. A language with a very limited vocabulary (especially one restricted to largely unhelpful words, e.g. "Justin Bieber", or "toe wart") is much weaker than one that has benefited from decades of cultural and generational digestion and iteration (i.e., a language that includes concepts like "however", or "on the condition that", or "art", or "gravity").