What those nuns did was segregate black children from all others who follow the teachings of Jesus. Why would he need to have black skin in order for black children to connect with him? He was Semitic so had the skin color of Middle Eastern peoples and to make him Black or White or any other skin color is to belittle his teachings. Catholics do that well, as do Protestants.

Why should Jesus' skin color matter to anyone? It's his message that mattered and was hidden as much as possible by all "Christian" churches. His earliest followers, those who either knew him or heard him teach, called themselves followers of the "Way", not "Christians" and understood that he never promised that he could or would save anyone from their own sins and "give" them a place in God's Kingdom.