Why we can't be good at everything!

In Book II, Chapter 1 Aristotle states that not everyone is born with the ability to be good at everything. Aristotle wants us to realize that we can't always be good at the things that we wish we were. We sometimes must let the people that are skilled in that certain area take over. There is a reason that we aren't all great teachers because there would be no one to teach. We are not all great homebuilders because there would not be anyone that was good at designing the interior. If we were all the same the world would be a very boring place because each individual would not feel special. They would not be different from anyone else and would no longer feel a need for themselves. I personally feel that we were given our talents for a reason and the talents were God given. You do have the ability to improve at a certain task, but you will never be as good as someone who has the talent originally.