The games really do pay a lot of attention to accuracy - although it's worth noting that some aspects of their portrayal are disputed by some historians. For example the Christianity thing - not that Christianity wasn't a big part of medieval European life, but most peasants in most of Europe only went to church like once or twice a year for the big holidays, so the portrayal in KCD may not be as accurate as it seems at first glance.

Anyway black people and gay people definitely existed in medieval times so in that respect KCD2 is more accurate than the first one.