Ariel - A no name actress or someone with Broadway experience. It worked for Hairspray and Nikki Blonsky. If they insist on a name, Emma Stone (who has singing jobs).
Prince Eric - (I hate myself for saying it) Zac Efron
Ursula - I adore Sherie Rene Scott’s take from Broadway, but I would actually LOVE to see Leslie Jones tackle the Sea Witch. Or Uzo Aduba.
Sebastian - Leslie Odom Jr is a quality dream cast. For the sake of difference though, I’ll say Aaron Tveit. Obviously, that Sebastian wouldn’t be Jamaican.
Triton - Idris Elba
Grimsby - Patrick Stewart
Scuttle - Weird Al Yankovic
Flotsam and Jetsam - Key and Peele