I deal with imposter syndrome by asking tons of questions and being totally up front about what I don't know - it helps that I have a sense of pride for what I know I can do - I'm a better lateral mover than most and that's helped me be useful where others struggle so it's okay when I'm struggling and they have the answers. Eliminating ego is a constant piece of the work.
The survivor bias is one that I think on pretty frequently. A friend that I mentored is a lot better than I am in technical ways but struggles in some of those areas that have nothing to do with tech - emotional regulation and people skills - and it's made the journey very difficult. I wonder frequently how I could have better taught those skills.
Edit to add: Homeless to senior eng? Holy cow! I wanna hear that story!