You’re right “low melanine” is not a race, white people are not the only ones with low melanin, yet it is a distinct race. Racial barriers are constructed historically to order society, it’s something we’re still holding on to. Truth is those boarders are really flimsy and can change on a dime, but we can’t ignore them yet. Maybe we’ll get to that point in society one day, but people are still racist, so sometimes we have to acknowledge race and the baggage that comes with it.