Calling someone "black" is an old school European slur, it doesn't mean their color is black dumbass.
Arabs ("Saracens") were called black in that period. Berbers ("Moors") were called black in that time period. When Native Americans were discovered, they were often described as Black. It could be used for ANY person with darker-than-white skin, or even just someone they wanted to depict in a bad light even if their skin was hardly dark at all.
This is Black Bart, the famous American outlaw.
This is Black Sam Bellany, the famous English pirate:
In old school Europe, being called "black" could mean anything from having a slightly swarthy complexion to just being considered a bad person. It had NOTHING to do with having Black African skin.
Imagine being so historically illiterate that your evidence for skin color is a generalized, meaningless European taunt.