drawing the line

I need to make something really elaborate and cool (doesn't move

No, your oc isn't too cringe or a Mary sue. Yes, it's completely fine that it looks similar to your other ocs. Yes it's completely fine that it looks similar to a Canon character design. No it's not uncreative. No the design isn't shitty. No the backstory doesn't have to make perfect sense or be all figured out. Yes it can be self indulgent or unrealistic or overly sappy. No you don't draw your favorite character too much. Yes you can flip flop between developing whatever characters you want. No you don't have to keep the parts of your character that you don't like or that make you uncomfortable just for the sake of consistency, realism or whatever else