We are primates, and when we put all the martial arts together (MMA) it turns into a match of who can get on top of and neutralize their opponent. A bear doesn’t have any way of attacking a primate if the primate can get to its back. As a human, we wouldn’t have the dexterity or strength to get around, cling onto a bear and choke it out, but a bear-sized gorilla probably could and once it does that it’s neutralized every mode of attack the bear has except writhing around and pushing it into other objects.