The human being is curious, and extremely dangerous. His nature is hard to comprehend, harder than more of the doctrines that humanity haves. I creep myself when i think of the nature human haves. Its perverse and pleasure seeker, superficial and full of prejudices.
The human and it social interactions rules over the moral, excluding the minorities just for the pleasure to fell better in their group, not knowing how it damages the auto esteem and the morality of the excluded group
This is reflexed in history with racism, social exclusion, religious war and other bad things. But in the cotidianity is easy as excluding a student or person, making a nightmare socialize. Is in human nature, but we need to put the morale first.
I think you blame a lot humans as bad things, they are not as bad as you say. Yes it is true what you say about minorities and exclusion but humans also have good things.