1.About human-dragon friendship.And that was in original story.
2.Yep, and i wrote earlier that they indeed existed , but not openly.But here we can see definitely open character dialgues , like ones to Arthur.
3.At least not allow opnely gay/bi and black at all( like black Morgana).In medieval times if someone married on black, well there's Very bad news for him.
4.I wrote earlier abou it - it's certainly possible to have black, bi, gay , whatever people in medieval fantasy.But much better if it is not placed on Earth and on entirely new fictional world rather than real world and based on existing fictional story.