Humans

What makes a human a human?  What differentiates a human from an animal?  Some of the attributes that come to mind are capability to think and love and a sense of morality.  I know there are a lot of questions regarding free will and the nature of morality and there always will be, but I'm not entirely prepared to address those right now. 

Are there certain qualities of a human that make you think that person has a higher "value" or "worth" than another human?  Are some humans "better" than others?

Is someone who is blind worth less than someone who can see?  What about someone who has an IQ of 150 vs. an IQ of 110?

Would you value someone who can't maintain a stable relationship lower than someone who is married?  

Are killers "inhuman"?

Are men better than women?  Are heterosexuals better than homosexuals?  Are whites better than blacks?