One example I take issue with in this is that 80s April looked more like a brunette than a redhead. The image we get of April having red hair is more due to 2000s / 2010s TMNT being gingers.
Plus the original April in the black and white comic was Hispanic with curly hair, and the live-action one in 1990 or whenever had curly hair like that even though she was made more caucasian.
That's not to say I agree with making a black April, but in fairness with how they turned comics Baxter from black>white in the 1980s series (looking at you, 90s Spider-Man!) I guess the series comes out neutral.
As for little mermaid, while it's true in respect to Disney, we should note that in the earlier-produced anime adaptations of the story the Little Mermaid (albeit she was named Princess Marina not Princess Ariel) was blonde and not a ginger.