Are they cases where this had been done already?
Yes, it's called The Team Normal
I have a character like this in my own superhero series, and she's just fine with it. Everyone in her family and close circle of friends seems to have some sort of power or quirk, but she treats them just like she would everybody else, and they do the same for her. They're really all just people. This character really tries her best to live a normal life, although lending a hand whenever she can to help with her family's endeavors at fighting crime. She rarely feels envious of her friend's talents, because she knows she has talents of her own. She feels no need to be abnormal like everybody else, she is who she is, and nobody expects anything different from her.
Overall, there's nothing wrong with being normal and is not necessarily something that needs to be "overcome". Normal people can do extraordinary things while still being normal. They don't have to be great at combat or have a super big brain, or have an unstoppable will. They've just got to believe in themselves and stick to what they're good at.