I think this is so individual that it becomes meaningless to talk about humans as a group and whether they need other people or not. It would very difficult to live a life that did not depend on others for at least some of our food and shelter and other necessities. I agree with you to that extent, about biological necessity. But emotional dependence is not as straightforward and I am convinced that it can be possible to get to a point where we do not need emotional support from others - provided, of course, that we want to reach that point. I am not saying that it is something that fits everybody but I don't think it is unhealthy or unnatural.

[edited to add: Maybe this is simply wishful thinking on my behalf, but I do hope I'm right.]