Before the Caliphates happened and christendom responded by creating the north south division, it was entirely unreasonable to view any part of the Mediterranean as distinct from the greater cultural whole aside from specifics about who specifically was living where at what time.

In fact Islamic empires regularly had an irredentist idea about their right to dominate the Mediterranean granted by being the true inheritors of the Roman Empire (especially after they took Istanbul)

Even in that time of division though, the typical Venetian had far more in common with the Typical Tunisian than they did with the typical Dane. Could even be part of how the "Protestant World" ended up looking so similar to a map of "the parts of Europe that were the least integrated into the Mediterranean core of Catholicism's historical forming grounds and institutions"

The comparison to modern travel is a bit off though... The vast, VAST, majority of humanity would never travel further than a few villages over in their entire lifetime. The 'mixing' of cultures isn't nearly as pronounced as you're suggesting. Consider that even medieval "France" was made up of over 6 distinct cultures with often different languages.

and that the moral lesson is don't be a racist

But is he a building?

What happens when your one black friend also happens to have Vitiligo and has a mischievous streak for people who ask if everyone in Africa looks like him

If you're passing them off as just regular people nbd in that setting then yeah that'd be inaccurate.

Then again, plopping in random white people into an Ancient Chinese setting would be pretty inaccurate too, even though there might've been "some non zero number" of whites over there at the time. Or in a random crowd shot of Nazi soldiers you plop in a few black soldiers. Certainly existed, but while funny it does make it seem inaccurate (and silly imo).

"Most historical settings"

Roman sure, especially as you get closer to Africa but nonzero elsewhere also

Middle ages, mediæval and renaissance almost certainly limited to higher nobility households either as nobles or "interesting" servants or major trading ports, especially closer to Africa.

The chances of a mediæval serf in a germanic country not looking northern Europe, or Mediterranean at a huge stretch, are functionally zero though, as anyone who came with the Romans will have been long dead with their genetics widely dispersed, and anyone who came over recently would likely be in an urban area, with marriage or higher level employment being their only chance to end up in a rural area.