Honestly its all up to interpretation. Mario games in particular (And Nintendo games in general) like to keep a lot of their ideas vague because they want people to project themselves on them. Is the reason Link still doesn't talk.
Do you feel the Inklings are black and represent you in the game? Sure, that sounds great and I am glad they make you feel included. Allowed.
Do you feel they are not "human" and not black but "tanned". Well, if you want to be adamant about it and see it as more a biological and fictional character, or feel that a canon distinctioin has to be made, sure, have it your way. You can do that. Just be assured that just because you think you are right doesn't mean you are, unless you are a developer at Nintendo, in which case where the fuck is Mother 3 you jerk.
Just don't be assholes and impose your opinions on others as facts. Also, as a rule of thumb, don't make fun or less of the ideas of others just because you have different values and education. People tend to make less of the real problems of minorities when they haven't see them for themselves, and sure, things nowadays ARE better, but there is still inherent racism and a clear solution doesn't exist, so it makes sense people get hurt when you make light of said issues. You never make dead baby jokes to a woman who had a miscarriage, even if said incident happened 50 years ago. It may be a weird comparison, but it has clear weight.
And full disclosure, I am mexican with a caucasian mexican father and a afromexican mother. We don't have the same racial issues in mexico as they exist in USA or other places in the world, but assuming they are not worth discussing or analizing just because you don't care or they don't affect you is, well, shortsighted.
In regards to Mario and Nintendo in general, they are a traditional company that is getting better about including more representation in their games. They also make weird decisions when it comes to them, based mostly in what feels right for the tone of the game. This is the same company that forgot Mario Sunshine existed when making Splatoon, and the same company that apologized for not including gay couples in Tomodachi Life (And promising in delivering them for a possible sequel). The same company who decided to include minish people on BoTW because they felt they wouldn't survive.
And, more importantly, they had no obligation to include different color skins for the Inklings on Mario Kart 8 Deluxe. They could have just added orange girl and blue boy and be done. But they went above and beyond and added the option. That has to make it clear they wanted to make it an option, and one that made sense within the universe.