Not every black person on Earth was a slave.
You have to be a complete idiot to think that. Steve McQueen made an excellent adaptation of Solomon Northup's true story that highlighted the horrific nature of slavery . Even the movie itself showed that there were plenty of free blacks in America.
On top of that, there have been plenty of kings, queens, princes, and princesses that were black. What you don't seem to understand is that you're part of the problem, reinforcing white supremacist rhetoric that would rather sweep the atrocities against our people under the rug with lies like "There's too many slave movies." We honestly should have more films illustrating the evils of slavery and how our ancestors endured despite it.
What exactly do you want? Because there's plenty of films that show black people making quite a bit of money. Films about African kingdoms (with the exception of Coming to America

) would not make bank because neither black nor white people would go see it, plus it would require a huge budget.