I still think they may not cast Ariel that young, though. I know that traditionally she’s only 16, but for the context of this show, if they want to give the character a full on, true love romance storyline, they could do that more effectively with an Ariel that’s several years older.
I’ve said this in another thread, but I still don’t get how 16 is seen as tradition for Ariel and not the other Disney Princesses. They’re all teenagers; Snow White, for example, is the youngest of the lineup with only 14 and she’s grown up enough to have a daughter in the show.
They could push her age up to around 20 and still keep the theme of the story where her father doesn’t want her running off. And around 20 makes her mature enough to have a proper relationship.