I thought I'd pull together a few different resources to demonstrate why I think there was more diversity in real european history than people think -- and by extension why I think fantasy based on medieval europe shouldn't shy away from including a wider range of characters if the author wishes to.
Saint Maurice (also Moritz, Morris, or Mauritius) was the leader of the legendary Roman Theban Legion in the 3rd century, and one of the favorite and most widely venerated saints of that group. He was the patron saint of several professions, locales, and kingdoms. He is also a highly revered saint in the Coptic Orthodox Church. He was also a black African.
Historical fencing manuals also show depictions of african combatants in European style dress.
From Volume I of 'De Arte Athletica' by Paul (Paulus) Hector Mair (Germany, mid-1500s):
From Fechtbuch by Hans Talhoffer (Germany, 1467)
The Moors invaded southern Europe including Italy, Portugal and Spain in the 8th and 9th centuries. The "Moors" were not a distinct or self-defined people or ethnicity. Medieval and early modern Europeans applied the name to the Berbers, but also at various times to Arabs and Muslim Iberians and West Africans from Mali and Niger who had been absorbed into the Almoravid dynasty of Morocco.
There are other accounts of Moorish travellers, ambassadors, courtesans (with their own servants), minstrels, chamberlains, and mercenaries from various sources throughout Europe, and especially England and Scotland.
This isn't the view I had of the middle ages watching Hollywood movies from the early to mid 20th century, but I think considering the politics behind those movies might be worth doing and then reflecting on what we actually know about people in the real middle-ages.