Intelligence is possessed. It can be built or wasted. It is about how a person processes information and responds. Character is how a person responds and acts to situations and opportunities. You can be of low intelligence and be a person of strong character. It's the stuff your parents are supposed to teach you. Personality is how you portray yourself to others and how you interact with the world around you. Everyone has some level of character and personality; good or bad. But intelligence can actually be measured - it is quantitative versus qualitative. You may dislike someones personality or character, but intelligence is more "scientific".

(Leaving aside such concepts as emotional intelligence - I am speaking only of traditional, classical means of scoring intelligence).

Because all people have the opportunity to learn more, thus increasing our intelligence. Now, how they use that information is another story...