I don't understand mathematics, therefore math is undreadable.
I don't understand music, therefore sheet is unreadable.
That is your problem in a nutshell.
Meanwhile, people here take a glance at the code and immediately get it, because it is written in a language they understand. These people tend to find it quite readable -- not necessarily an example of most pretty code, but nevertheless readable.
I may be a C noob, as I already and in an honest way stated in the very first post, but my points still stand. Those are not some subjective things. It is very clear, that those things add to readability, yet the code does not have them.
I'm a person who has written a lot of c, readable and unreadable. It's not that folks don't care; I find that notion slightly offensive. It's that a lot of c programmers care about different things. And, especially those of an older school have a different mindset.
When you read c source, especially that labelled "exercise in minimalism", you should approach it as hallowed. Enter the file with a sense of reverence; lose the ego; ask not why the file wasn't written in service to you. As you have here, tsk tsk. Expect a challenge, a puzzle. Ignore the variable names; they may be misleading -- learn for yourself what role each variable takes on each line -- some of us will reuse a variable for multiple purposes throughout its lifetime. Humble yourself with the understanding that the code was not written for you. It was written for a machine infinitely more patient and methodical than you. Use that machine to execute and debug, watch and analyze, to discover the true meaning.
But, at least to me, it's nothing like poetry. Anyone, without any specific formation, can read poetry and understand something of it. In poetry, artistic license is the exception, not the general rule. The deep meanings, intertwines between form and content, the attention to metre, the use of allegories, and so on, will not be consciously grabbed by every reader. But still anyone that has the base language knowledge required can read it and find some sense to it.
Wait, you are telling me, that people write even less readable code in C? Perhaps you are right. Perhaps people can really be that much without care.
It still does not make this code "very readable". If it was very readable, I would have a vague idea about what each of the "functions" does from reading its name or its docstring. Oh wait, there is no docstring at the beginning of each of the "functions" and the name consists of one word, sometimes abbreviated word. And the variable names don't give me hints either. I think our definitions of readable code simply differ quite a lot. When I write code myself, I am unwilling to accept code on that readability level, but we probably have different standards.
Perhaps for entertainment purposes only, you could show me a real C nightmare. I do honestly believe you, that there is worse ;)