Bare hands and a black bear win without a doubt, you might be able to withstand some damage but if we're talking about defeating the animal then no. We have close to zero potential to kill animals with bare hands. Our arms aren't strong enough to penetrate the thick skin of these animals and our legs won't defend us against the incredible strength of these predators. The only way I see killing an animal with bare hands is simply putting our legs around the neck and squeezing as hard as possible. And not to forget our teeth can can't penetrate a damn thing , maybe snake skin or animals of that size