Why does any country get to lay claim on a chunk of seafloor that has been uninhabitable for land animals far longer than humans have been around as a species?

Why does any country get to lay claim on a chunk of seafloor that has been uninhabitable for land animals far longer than humans have been around as a species? United Nations Convention on the Law of the Sea https://en.wikipedia.org/wiki/United_Nations_Convention_on_the_Law_of_the_Sea https://en.wikipedia.org/wiki/United_Nations_Convention_on_t... It's true this is unfair to marine animals, but that's really their fault for not attending the meetings when the treaty was signed.