Note post 80, you’re largely correct. I’m sure they were captured in North Africa. But in general the number was small, and they were persecuted in the name of racial purity. Though Hitler liked Islam, and Persian, sorry, they changed their name to Aryans (Iranians), he had contempt for Arabs as well. They leave certain parts out of the Arabic translations of Mein Kampf. However once in power, blacks were a small bit above Jews and Roma, a bit above Slavs who were worth enslaving, and would have been eliminated.
I see what you mean. Also, I’m sure the Axis must have captured blacks in the British Army, though I’ve never heard of their treatment. Hitler seemed to view blacks as a harmless though inferior group (as opposed to a menace like communists).