Beyond the natural 'necessities' to survive and reproduce, every human's ultimate purpose is to further the spread of humanity and civilization to every corner of the Earth and the universe. Aggressive to a fault, and too intelligent for it's own good; however, some day, it may save the Earth that so long endured punishment at the hands of the human cancer. Humanity is not a plague. Western society is. However, it is the only way, and progress comes at a price. Some day the Earth will fully heal.
Intelligence is a gift to homo sapiens, the thinking man. However much we may abuse it it is better for good than evil, and some day it will shine through.
Humans also have very weird sense of beauty, they consider ugly things (for example: snow mountains) as "breath taking". In most cases they can't even use the simplest logic. Paradoxically, everything in their life must be in a perfect order, everything must have a number, a name, every single item has its very own place in their homes, work places or wherever. They also like lots of entertainment and they can't remain serious when required. It is also worth noticing that in the human societies the Emotional Quotient (also known as EQ, also known as inter personal intelligence or emotional intelligence) is far more important than the actual Intelligence Quotient, in other words: it's better if you are charming than if you are intelligent. Humans have created over 3.000 languages and there are more than two hundred countries. The reason why humans don't want to unite is unknown, although they use excuses such as "culture", "languages" and few other things. In human societies being cynical is perceived as a disadvantage, a bad element of personality. Humans are also very ignorant and arrogant.
A very good example of their ignorance is fiction they create. For some unknown reasons they think that other sentient races - if they, of course, exist, are exactly same as them. A perfect example of this are the fan-made Argonian related modifications for the video game The Elder Scrolls IV: Oblivion, where humans are showing their lack of most basic knowledge and logical reasoning by mistaking reptiles with mammals et cetera.
The only hope for stopping this madness is the nuclear weapons arsenal, which is possessed by some countries, such as Pakistan, India, France, United States, China, United Kingdom or Russia.
Note: This is not a sarcastic entry.
This faculty turns in upon itself, however, when the attempt fails, leading to such emotional conflicts as self-loathing, bias against more succesful others, self-worship, or sublimation of individualism into a group mind.
Humans have borrowed many traits from other species such as hunting for pleasure ( from cats and squids ), enslaving other species ( from ants ), protecting and nurturing other species to gather products from them ( from ants ), spoiling other creatures habitats by their own constructs ( from beavers ), and creating and sharing habitats with other creatures ( from corals, rodents and birds ). Humans have invented several concepts for themselves, such as artistic endevour for its own sake, resource gathering and stockpiling for its own sake, ignorance and self-delusion as a natural right, love and attraction not solely for the purpose of reproduction, worship of the different, lack of diversity as a positive, and worship of the identical.
Humans are capable of percieving that they are less than what they imagine themselves to be. This is not only their major problem, it is also their major strength.