Someone once told me somewhere, that if I am trying to learn rust, I should learn C first, so that I know how to shoot myself in the foot, learning to avoid doing so

This is stupid advice. If you want to learn rust then learn rust.

So thats what I did (somewhat) for the past 6 months. I wrote some stuff in C

In that time you are no closer to learning rust. If you started with rust you would know it by now. Rust is not harder to learn then C. If anything C is harder to learn as it's compiler doesn't guide you at all.

You don't need to learn C to appreciate the borrow checker. I find beginners just accept whatever they are first taught. It is only really those that come from C the put up a bigger fight when learning rust.

And 6 months in a language without a borrow checker is not really long enough to learn the reasons why a borrow checker is useful. Not without a good guide that focuses on that. Which most c books don't. The best way to learn it is with rust that actually tells you when you mess up.