Why are people so hard to understand?
Actually humans are pretty easy to understand from a "whole" perspective. Humans are given situation and they react to that situation in different ways. Now, speaking of the "whole"; it is easy to understand that humans seek power and control of their environment. Humans require the feeling of accomplishment whatever they think it may be. In society humans are even easier to understand because they are all copying what their neighbour is doing, everyone wants what everyone wants, no one wants to feel "left out". We can even compare humans to a flow of ants. Ants act as a colony and they are working together to accomplish what they need to accomplish. Same goes for humans, they do what seems necessary to accomplish their goal(also working together). So say we are aliens it is easy to "understand" humans as a whole because we are all the same and we just need to be observed by a more sophisticated being than ourselves. This observation would be easily done because humans are sheeples (sheep+people = sheeple). Thus, if we are talking about understanding the human brain, the essence of human life, the why of our very existence...then this is more about understanding life in it's whole and not simply the human. Try to think about this: do you know exactly what an ant is thinking about? Is this cow thinking? How could you truly know? And to question our existence would be to question the existence of everything. So everything is hard to understand not simply humans.
Although my point made, humans are very complex and it is difficult to grasp the essence of their mysteries. The human brain is so complex we can't understand the biological computer that is in the human skull. Also, we barely know anything about Earth. Learning about the humans mysteries and complexities would also bring us to understand more about our world and our universe. Therefore, the understanding of humans will grow alongside the understanding of all lifeforms. There are connections to make with everything, everything is connected and there are so many causes and effects to human behavior that it is for the moment being "impossible" to understand certain human behavior and their nature. We can't even understand the essence of our own existence, we have so many uncharted paths to walk onto. This is why it is hard to understand humans if you look at it from this second angle.