I disagree with this. Humans are not "just good enough". Prior to creating agricultural and large civilizations Humans spread out and successfully inhabited every continent on earth. Humans have very high level of dexterity. Thumbs and ball & socket joints are every bit useful as fur, sharp teeth, horns, or etc. The diversity of our diet, what we can eat, is/was also a major evolutionary advantage. Our dexterity and diets allow(ed) us to eat food collected from underwater up to food located atop trees. Human also have tremendous endurance and mobility. We can cover very large amounts of ground in a day. Our eyesight has depth and is in color. That is much better than merely "good enough". A lot of animals have poor color vision and depth. The list goes on and on. Humans are excellent swimmers, we are able to vocalize (trick prey or intimidate predators), we are naturally great at carrying things thanks to being bipedal, and etc, etc, etc.