To the Hans Christian Anderson version. I suppose I should not have referred to that as the "original." See https://www.storyberries.com/fairy-tales-the-little-mermaid-by-hans-christian-andersen/

In his version, the sea witch says much the same thing that most horrified me: "You have your looks. Your pretty face. And never underestimate the importance of...BODY LANGUAGE!"

In his ending, she is redeemed, not turned to sea foam. If she is very, very good (and you, too, dear child) she may be able to earn her own soul. (The idea that she could only do it through getting a human to fall in love with her is outrageous, in the first place - but in a way, Anderson snatched the story out of the literary Dumpster at the last minute and gave her SOME agency. Disney didn't even leave her that, really.)