As long as it fits the theme I am fine with it.
I'd find black skinned knights and asian romans too politically correct for example, in that case it would break the immersion of the theme.
However they could make an entire pirate crew consist of black clickies.
And they did have a black gladiator in the roman theme. Yes gladiators are slaves, but in this case it was alongside white gladiators which showed accuratly that they enslaved everyone and it was not based on skincolor.
So that did allow for a black gladiator to be the hero. In fact I believe they did just that with the official animated little movie. He was captured, became gladiator, fought and found his freedom.
So what I'm saying is, go for diversity but dont impose it where it is out of place. Instead there can always be looked for plausible solutions instead.
In a medieval theme, black clickies could be traveling merchants dressed in middle eastern fasion, that could go well with a merchant ship.
Adding the occasional asian pirate in the pirate theme seems like a good move. Now we just need asian and black female pirates. Or maybe a female pirate with an eyepatch, hook or wooden leg. They never had that.