Another animated anthology series is 1998's Australian Timeless Tales series (which is different from the classic WD anthology, and the early nineties Hallmark anthology). This one's a light-hearted series for young viewers that revisits a bunch of classic fairytales with its own twists.
In its The Little Mermaid episode, there's a whole new enviromental subplot where human have been dumping their rubbish in the sea, to the anger and frustration of the merfolk. Miranda, the little mermaid of the title, in particular can't wait to go to the surface for her ascension to give them a piece of her mind via song. Another subplot is how there are two rival kingdoms where the kings that have (somewhat) agreed to settle their differences by marrying their children. Prince William isn't very keen on the match, as he's heard that Princess Clarissa is a selfish, vapid young lady. While William and his father are traveling to the Clarissa's kingdom, the rubbish dumped over by sailors cause a whale to be blinded and go berserk, hitting the ship and causing it to sink. Miranda, who is on her merday and witnessed the thing, saves William and takes him to shore.
The set-up is already incredibly different, setting up the characters and their motivations onto vastly different paths from the fairytale from the very beginning. In particular William and Clarissa's part of the story seems to be the the backbone, and Miranda's role is how she intersects with their story and changes it.
Thanks to Omar for letting me know about this version!