On modern computers, it is impossible to write correct C programs that are agnostic about the true size in bits of the "flexible" types char, short, int, long and long long.
If your program must depend on assumptions about the size in bits of the integer types, those assumptions must be made explicit, by using types like int16_t, int32_t etc.
Writing correct programs that are agnostic about the integer sizes is possible only in programming languages that allow the programmer to install an integer overflow handler even if the CPU does not generate a hardware exception for that, in which case the compiler must insert appropriate overflow checking instructions that would invoke the installed handler when necessary.
This problem did not exist on old computers, where there were hardware exceptions for integer overflows, so even in C you could install a signal handler for SIGFPE, which would also be invoked by integer overflows.
I have never considered that this is an acceptable solution, which is why in decades of using C, during which I had many times to port programs or even entire real-time operating systems between different ISAs, I have never used those minimum sizes.
Instead of having those minimum sizes, which I consider useless, C should have had since the beginning, besides sizeof, which gives the size ratio between another type and char, another operator or macro to provide the size in bits of any integer type.
With that, it would have been possible to use types like short, int or long in a portable way.
Nowadays, there are _WIDTH, _MAX and _MIN constants for the integer types, but those have been added relatively late to the language, together with the integer types with specified width, for which those constants are superfluous.
#include <limits.h>
#if INT_MIN == 32767 && INT_MIN >= 2147483647L
# error too small
#else
# error just right
#endif
UNIX was ubiquitous in the data center well before Linus even posted his first version of Linux on USENET.
Everything ran on SunOS, HP-UX, IRIX, AIX, etc.
C was pretty much ignored on 8 bit home computers, outside some toy compilers for CP/M.
In the 16 bit days, it was yet another language alongside BASIC compilers, Pascal, Modula-2, Assembly.
C is so tied to UNIX, that POSIX had to be created so that any non-UNIX operating system could provide a cozy home for their C compilers.
UNIX/POSIX is for all practical purposes the runtime most C applications rely on, there are naturally some exceptions like free-standing or Windows (which eventually gave up and add to start improving its support).
It is only due to historical accident that Microsoft gave up on Xenix, instead of replacing their MS-DOS efforts.
And many projects properly abstract their OS layer so they aren't tied to POSIX.
Maybe Unix is tied to C, but C isn't tied to Unix.
?!? What a claim!
Traditionally this was a profitable niche, Microsoft would like to take a fat piece of that, and instead what happened is that Linux destroyed the profit margin. A million dollars overhead that would have kept a hungry UNIX® vendor alive on your project didn't turn into an extra million dollars on Microsoft's balance sheet, instead it evaporated because Linux is "free". And so then Microsoft lost interest.
WSL is Redmond going OK yeah, here you go, an actual Unix.
The point still stands, that POSIX checkbox was relevant enough for spending the money in engineers salary during Windows NT 3.51 development.
C was invented to rewrite UNIX in a programming language that made it easy to port UNIX between machines.
So what you're saying is contradictory. You're saying the underlying motivation of C was wrong or unnecessary (porting UNIX to different hardware architectures) but C won because that underlying motivation (easy porting between hardware architectures) was partially right.
Your position is now that C didn't need UNIX as a stopgap, which is weird because your argument gains no weight (basically saying C's dominance is sheer coincidence) if it's true but if it's false you're just plain wrong.
On the consoles it took until PlayStation for C to take off among game devs.
Additionally many Amiga games used Blitz BASIC and AMOS.
Anyone involved in the Demoscene early days would be 100% Assembly as well.
On PC, it required until Watcom with its great MS-DOS extender for devs to finally move away from Assembly in mass.
It depends: for the classic 8 bit home computers, games were mostly written in assembly. Later DOS games were commonly either written in Pascal or C, but quite a bit off Assembler code was often used for the more performance-critical code sections.
I was there, Gandalf ;)
(and note how I specifically wrote "dominant high level language", not "dominant language", since assembly coding was indeed very relevant on those machines, for UI apps 100% assembly was quite rare though, and hybrid C/ASM seems to have been more common).
In my part of the Iberian Penisula it was Turbo Pascal on PC and AMOS/Blitz Basic on Amiga.
With lots of inline Assembly anyway.
This is why I think so many C developers have no clue what they are doing. They just take whatever decision was made in C as gospel instead of thinking of everything being up for negotiation.