Dichotomy

There are two common views of humanity: one, that we are all fundamentally the same, with the same needs, desires, and basic make-up; the other, that we are all unique individuals who each have something entirely our own to contribute to society. This is a dichotomy. If we are all the same, how can we all be unique?
Today I was watching a movie, with the typical story: evil, trouble, struggle, redemption. I found myself pondering the fact that these elements always show up in some form or another. It seems that struggle is the greatest common denominator in stories.
Why does struggle resound with us so deeply? I think it indicates some common denominator in people. That each person needs certain things. Now I'm sure several experts could spend hours arguing what those things are, but I don't think they'd contest the fact. I would postulate things like acceptance, love, purpose, community. Whenever you get someone to talk to you on an honest, real level, they will often say things that sound very familiar- very like things that you've heard from other people at similar times, or things that you yourself have thought/felt. So my question is this:
If we are all so similar, what is it that differentiates us? Into classes of people, into individuals?
I mean, just as the above is a fact, it is also true that people are different from one another. They do have very different points of view. I don't need to prove it to you, you know it. Just think of someone who's completely different from you, and their friends. And then think of your community, and all the fascinating or boring people in it. You know they're not all the same. That's why one of the most popular sappy plot lines sounds something like "we're all human" or "we're all part of the same big family" or "we're not really all that different" etc.- every time someone realizes it for themselves, it feels like such a discovery that they have to tell everyone else about it (and if you're anything like me, it can get plenty annoying sometimes).
Still, I find I have to acknowledge the truth of it.
With that in mind,

what makes a person unique?
I wonder....