Evolutionary theory and difference

When you talk about the evolutionary theory, you say the strongest survive.
But then why are we all so different?
The strongest survive.
Dosn't it meen we all should be identical, or almost identical?
You can say we are, but if that's true, why does we have so different interests and have so different strengths and weaknesses?
Yeah, maybe if the difference only was a little bit of variation, but still connected and within the same subject?

I think the simple answer is that we need all sorts of talents to build up a community like ours, and without the difference between people, there wouldn't be any chance that we would develop ourself, and the community would stop developing too.
We need suport from each other, else we can't continue the development, and that would result in the suspension of the evolution.
That's why we need to be different.
And it's also a good way to put variation in our daily life, and make the day different from the last.

The evolutionary theory says the strongest will survive, but it's not only one, who is the strongest; it's a lot!