Is that really true? Do traditional Black African spiritual systems disparage black people?
Yes they do.
In Igbo traditional religions, twins were considered unclean and thrown into the bushes...literally.
In Congo today, pygmies are eaten as part of traditional African religion.
Charles taylor kept a batch of daily human blood to drink from based on the advise of African "traditional religion".
Salif Keita, the famous west African albino singer, describes witch doctors coming to try to hunt him to eat him for powers. This is present with albinos today.
The "traditional religion" of Africa and everywhere else is to worship one God and to honor his human creation. The demonic realm is what enters upon humankind to get them to corrupt that. In 337 Rome, the demons did it through Constantines adoption of Pauline paganism. In 1972 South Central, they did through the Bloods and Crips. In 1945 China, they did it through the introduction of communism and the insane mao zendong.
The demonic realm does this so that humans may turn away from their creator and then subsequently oppress each other without care (as the trinitarian protestant white man did to black folk.
Islam invites all to the worship of their lord and to the best path. But only those who follow guidande will benefit.
Say, “This is my way. I invite to Allah with insight—I and those who follow me. Glory be to Allah, and I am not one of the polytheists.”
-Surah Yusuf, Ayah 108