Here's my full-disclosure: if your characters are written honestly, they will have some part of you in them. Any truly earnest character is, on some level, a "self-insert". Don't be ashamed to draw from your own life and experiences to inspire your characters. Be happy that you're self-aware...
Haha, this was my cringe, too!
I used to write a ton of fanfiction on Wattpad/Quotev. I would write human-in-pony-world fics, and I had my Sonic OC's, Nitro and Frost the Hedgehogs, fight Sonic.EXE. My most popular story was "Evil Pokemon" with like 130 reads a chapter. Needless to say, I...