Explaining Llm.c in Layman Terms

Are there a lot of people who know all about tensors, deep learning, and PyTorch but have no idea what C is?

They probably know what C is in the very general sense, but there are lots and lots of people people who know all the deep learning stuff but have never written a line of C or really understands the when/why you might want to use C and the benefits and limitations of the language. You have to remember that a lot of people currently working in this space don't come from a computer science and programming background and don't have that general background knowledge of computer science.

I'd guess there are a lot of such people. Probably most who do deep learning don't know much C. Or even much general purpose programming.

I think so. Many people have some knowledge of high level LLM stuff, e.g. by using tensorflow, pytorch or similar. All of these libraries intentionally hide a lot of the details behind abstractions and having an example where every single detail is made totally explicit seems like something that could be very valuable if you want to understand the topic deeply.

I think many practitioners with statistics or pure mathematics background have very little experience with systems level programming and program primarily in very high level languages.