To list something: C teaches memory management, memory addressing, stacks and heaps, some disassembly, binary interfaces. Basically, you see the layer on top of machine language. Python, Go, etc. are a layer on top of that.
Rust and C++ teach these things as well, but C keeps things minimal so you see the ideas more clearly. A lot of languages are written in C, forming a common way to think about implementation and problems, one you see glimpses of working in almost any other language as well. A lot of "why is it like this" questions have answers beginning "because in C..".
The FFI part is due to the extremely stable and simple ABI. Compiling C produces predictable and known binaries, setting a lowest common denominator among languages (for bettet or for worse). Thus knowing the capabilities and limitations of C is useful even when working with other languages.
A lot of this knowledge can be grasped quickly and you will get reminded of them for the rest of your programming life, so it's not necessary to dive deep into C to get the knowledge. C just provides the shortest and cleanest introduction, and you can quickly move forward without missing a beat really, since a lot of the stuff is so universal.
I'd go with C first. Rust would teach you everything C does and more, but C will lay the foundation in cleaner strokes. This will help you later no matter what language you decide to learn next. C is also in a way the language of the FFI, so you are very likely to need it in the future regardless.
Rust and C++ teach these things as well, but C keeps things minimal so you see the ideas more clearly. A lot of languages are written in C, forming a common way to think about implementation and problems, one you see glimpses of working in almost any other language as well. A lot of "why is it like this" questions have answers beginning "because in C..".
The FFI part is due to the extremely stable and simple ABI. Compiling C produces predictable and known binaries, setting a lowest common denominator among languages (for bettet or for worse). Thus knowing the capabilities and limitations of C is useful even when working with other languages.
A lot of this knowledge can be grasped quickly and you will get reminded of them for the rest of your programming life, so it's not necessary to dive deep into C to get the knowledge. C just provides the shortest and cleanest introduction, and you can quickly move forward without missing a beat really, since a lot of the stuff is so universal.