Black people are black for the same reason that white people are white and brown people are brown and olive skinned people are olive skinned. It is due to the varying presence of the chemical melanin in the skin. Underneath, we are all the same as the apostle Paul said:
Acts 17:26 And He has made from one blood every nation of men to dwell on all the face of the earth...
For all we know, Adam and Eve could well have been black. Jesus himself was semitic and so almost certainly olive-skinned.
People who belittle others on the basis of something as trivial as skin colour demonstrate their own insecurity. They have so little in the way of feelings of self-worth that they will stoop to anything to feel superior to some other easily identifiable group! Such hatred is born of ignorance and will end in the rejection of such a person by Christ at the judgement.
It is an interesting facet of the judgement seat that Jesus said:
"And the King will say, 'I tell you the truth, when you did it to one of the least of these My brothers and sisters, you were doing it to Me!' (Matthew 25:40)
"And He will answer, 'I tell you the truth, when you refused to help the least of these My brothers and sisters, you were refusing to help Me.' (Matthew 25:45)
So, whom do you consider to be the "least"? You will be judged on the basis of how you treated them. If you consider black people to be the "least", then you are called upon to love them the most. Your eternal life depends upon it!