Someone wrote it though. It’s not a blackbox that’s evolved independently for millions of years. We as a species know how to build one, since we did.

I suppose this makes sense, but at a personal level, the two scenarios seem similar. Interpreters & compilers are blackbox to me, at least. I have no idea how they work, and I wouldn't be able to make one for myself. But sure, someone could teach me.

I can build libc all by myself from source

Or more closely, give me the .o files for my architecture, I somewhat understand the calling convention used. I should be able to make use of it.