First, the definitions.
human - of, pertaining to, characteristic of, or having the nature of people
nature - the particular combination of qualities belonging to a person, animal, thing, or class by birth, origin, or constitution; native or inherent character
evil - morally wrong or bad; immoral; wicked
good - morally excellent; virtuous; righteous; pious
Now my question to you: Is human nature wrong or right? What is your theory on human nature? In my opinion, that human nature is naturally right, as the earliest men had to come together to survive. They held no prejudices, were not immoral, did not steal, and only took what they needed. However, overtime, the knowledge of humans, not intelligence, expanded. Humans used that knowledge to acknowledge delusional superiority and abuse of that superiority. Those who were convinced they were a lower class learned two things: to achieve that rank and to follow. Those who wanted to achieve that rank learn to methods of tyrannizing those in the same class. Over time, the ones being tyrannized learned from the tyrants and thus, the modern human nature is born, which one may or may not define as "evil".
