It's been a long time since I saw Disney's original animated "Little Mermaid" movie...but I don't recall them delving into any explanation of the racial/ethnic heritage possessed by Ariel and her familial lineage. For this reason, it isn't pertinent to the story that the live-action Ariel be played by a White actress. In theory, the mythology of mermaids would allow for their species to be of all complexions. So, under that framework, a Black actress portraying live-action Ariel is completely believable.

Although I do remember, months and months ago when news of Haillie Berry's casting was first released, Sheryl Underwood on "The Talk" suggested that they could maybe alternate red-colored dreadlocks amidst Haillie's hair for the role.

I remember the live-action "Cinderella" remake that "The Wonderful World of Disney" broadcasted in 1999. It starred Brandy Norwood (as Cinderella), Queen Latifah, and Whoopi Goldberg. But the cast, as a whole, was multiracial. I remember wondering, as a high school junior, how the Black queen and the White king ended up having a Latino son who'd end up functioning in the role of Prince Charming. One of my classmates dismissed me by saying, "Okay, but that doesn't matter." It didn't occur to either of us, back then, that the Prince Charming character may have been adopted by the interracial royal couple. They could have easily inserted a simple line of dialogue alluding to that backstory, once the actors were cast.