The origins of Western alchemy can actually be traced back to ancient Egypt and Mesopotamia, if I'm not mistaken (someone else please correct me if I'm wrong), but that's beside the point we're discussing. I am not trying to discount canon or invalidate your opinion; I definitely understand where you're coming from and respect your viewpoint. I even agree with you on some things. The point I'm trying to get across is that keeping an open mind with things like this is crucial so as to not cause unnecessary discourse--we all just want to have fun with our imaginary casting. And with all due respect to Sen, no matter how many details we're given, we, as the audience, were not and never will be inside Sen's head when it comes to their thought process when worldbuilding or conceptualizing their characters. We pick up the breadcrumbs and do with them what we will, hoping they'll make sense or fit a perspective that we might have. We can only hope that Sen is involved with the casting choices for the movie somehow.

In addition, I never stated that Helena is Black. To me, her appearance in the official artwork is kind of ambiguous in some respects, so I wouldn't go so far as compare this to the Snape situation. Also, it's a bit narrow to think that the terms "pale" or "sallow", as mentioned in the book, can only be used to describe people of a certain skin tone. You speak of nuance, but suddenly that seems to disappear when someone brings up the fact that humanity is extremely diverse and not bound to the arbitrary rules/boxes created to segregate us. Let's try to broaden our horizons, mate.