A big part of that is because we evolved to be social animals. A single man alone in the Amazonian jungle would have a hard time surviving for an extended amount of time. A tribe, though, would have better prospects. If you are alone in the wilderness, you're presented all the time with insurmountable trade-offs: Build shelter and you won't be procuring food, prioritize food and then you won't have a shelter to protect yourself. Working in a team means bigger projects can be tackled, that different needed things can be done in the same time. And this is one of most important things for the evolution of humans, not only the intelligence, or the ability to make and use tools, but also the ability to live in society, to communicate and build a culture.

The homo sapiens is indeed a remarkable species. But what really make us what we are is not the individual per-se, but our society. Homo is great, for sure, but what is really impressive is not the individual Homo, but humanity.