C is not relevant any more, not sure what world you are living in. it only has any relevance because it was the best option at the time decades ago, and so people are forced to use it when making syscalls. thats it.
C is still in the top five in the TIOBE index today.
first of all, no. plenty of OS are made in other languages. also, the big OS WERE written in C, and only remain so in order to avoid redoing millions of lines of code.
> and then a interface to them are given through wrappers in other languages
again this is only done because the OS is using an outdated language, so people are forced to work with it.
> C is still in the top five in the TIOBE index today
that doesnt matter, this does:
"you're wrong man, C totally has a bunch of code being used thats private, I swear". you could say that about every single other language. only thing that matter is what can be measured. C is dead man, you are just in denial. its an old crap language that hasn't been relevant in at least a decade. if you need some evidence, just look to the fact that after decades it still doesn't have a package manager, so many people laughably just vendor code when working with C projects.