The specifics of C’s design could barely be less important. In the 70s it was one of countless ALGOL derivatives churned out on-demand to support R&D projects like Unix.
Unix succeeded, but it could have been written in any of these languages. The C design process was governed by the difficulty of compiler implementation; everyone was copying ALGOL 68 but some of the features took too long to implement. If Dennis Ritchie had an extra free weekend in 1972, C might have a module system. But he didn’t, so it doesn’t.