How do you approach open source repositories without feeling like an imposter?

I looked through some of Rust's source code and also rust-analyzers LSP implementation but understood close to nothing. It happens fairly often and I don't know how to break the cycle. I enjoy writing Rust but my projects have been fairly basic, I did a bit in bevy and also explored the backend bubble a bit. But that's it and I never seem to be able to escape that bubble. How do I make the jump and understand how actual code works... I wrote my own kernel module for FreeBSD, I did a big of grammar and parsing, wrote a firmware for a small Arduino robot, did pathfinding... but those are all projects that are at max 2000 lines of code. And the moment I look at repositories on awesome Rust or similar ones I feel sooo stupid..