I was really worried the ending would be deep and depressing when we find out that the bottled message was in fact really old and the scenes with the little girl were actually time skipped in the past and
A) The girl was really old and had died or
B) was living out her life free already or
C) my best theory the girl having never been rescued, grew up to become Medussa since you dont see them in the same shot until a bit into the movie.

Then around halfway through realised it was a Disney movie and would never deign to impress me with such a plottwist.