Imagine the world without the types of people that are in it today. For example; the good, bad, priests, murderers, rapists, pedophiles, bank robbers, etc. Without all of these people, who would we be today? People balance one another out in every single way, shape, and form. Without all of the so-called "bad people" in the world, how would we judge who is a "good person" or not. For all we know, the world could change in the future and the people that we all frown upon and have bad thoughts about, could become the good people. Therefore, the good people that we have today would not exist. They would simply be overpowered by their opposites. The fact that this has not happened yet is purely based on human nature. We all learn everything from someone. Whether it is learning how to walk or or playing a sport, we had role models to guide us. In a way, we have some resemblance of all of our role models in our personality. We learn to build off of these people and become the character that you are today.
For example, if you were all by yourself in a world of nothing, there is no way of telling what type of person you would become. This all proves that humans will never be fully explained, no matter what, and that what we do with our lives and our personality is now, and will forever continue to be a mystery.