Castro made fools of a lot of black politicans, including Obama. So did Che, who was an open racist. Latin America is enamored of communism from the Pope to the childish voters who believe in papa government.
The Castros were some of the richest people in Cuba. The Cuban government is lily white at the top because the Castros hate blacks.
As for black only groups, why is it illegal to have a whites only group? Of course, racism was made worse by Darwin, but the Democrats depend on the black vote to maintain power. Imagine all the decades of dispute over melanin.
"What is man, that thou art mindful of him?"