First, please remember The Two Cakes Rule!
Just because something similar exists doesn't mean that your version isn't needed, or even that your version won't bring something new and different. Two characters looking the same doesn't mean that your story will have the same themes, that the characters will have the same arcs throughout your story, or that your stories would even be able to resonate with the same people.
I've definitely had this happen -- it was a rough feeling to get really really excited about this new story idea about glitches in a video game the literal day before I saw Wreck-It Ralph in theatres. But even though that was a huge blow at the time, a couple days after I saw the movie I realised two things: 1) that by the time my story is all put together, Wreck-It Ralph will not be The New Popular Thing anymore and I don't have to compete with it anyway, and 2) that glitches and video game stories aren't a new concept anyway -- so this movie's existence doesn't mean I can't do my own take on it.
I can definitely see wanting to push away from an established character design if they just feel too close -- if you suddenly realise that you've literally made Sailor Moon and you're worried the similarity'll be distracting, I could see myself changing a colour scheme or tweaking her hair -- I've done similar things myself. But I don't think Looking Different From Everything is what makes a character or a story original. What makes it original isn't that surface level stuff -- it's what you want to say about this character, and the story you want to tell, and what it means to you.
There's this video game that has weird cult following called Deadly Premonition. It's not very well-made, and it mostly gets described as a Twin Peaks rip-off. It isn't even subtle -- the characters have very exact, obvious parallels with that show. Yet the game gets a strange amount of praise -- those who love it really, really love it. The creator is well-known enough for this work that he was able to start his own gaming studio. Why? Because he put his heart and soul into this game and it shows -- it's weird, and unashamed of how weird it is, and that makes it feel special, even when the parallels and inspirations are super obvious.
Being "original" isn't about being different from everything else -- it's about being true to your own self, and what you really want your story and songs to be!! I totally get that it feels rough to see someone hitting the same notes you wanted to hit, but I promise you, that doesn't make you unoriginal!!