because, despite what many people assume, humans are just not the same species like any other animals. We did not evolve from fish/whatsoever (there are no explicitly accurate empirical evidence for that, don't bother arguing with me for this pls), so the notion that we somehow evolve so much better in others in terms of intelligence is bs, we are already better because we are humans.
Language is a skill simply unique to humans, it is not an evolutionary trait (the origin of language is one of the greatest mystery). For anyone wishes to debunk the notion that humans is the same as other species, please explain the existence of language in humans, if you can, you can collect your nobel prize. This, and among many other things, are the real gap in evolution that general science didn't actually bother to explain, hence the theory of macroevolution in humans are actually full of holes and errors.
To anyone who wants to debate about dna and macroevolution with me, pls don't, just explain and prove the origin of language and answer op's question (which no one has), then you would have been right. All mumbo jumbo theory about evolution and stuffs will still break under the origin of language problem.
Op has the right question, now op just need to search for the answer.