The main reason C and Unix became widespread IMHO is not because they were better than the alternatives, but rather because AT&T distributed them with source code at no cost, and their motivation for doing that was not altruistic, but rather the need to obey a judicial decree or an agreement made at the end of an anti-trust court case under which IBM and AT&T were ordered not to enter each other's markets. I.e., AT&T was prohibited from
selling computer hardware and software, so when they accidentally found themselves to be owners of some software that some universities and research labs wanted to use, they gave it away.
C and Unix weren't and aren't bad, but they are overestimated in comments on this site a lot. They weren't masterpieces. The Mac was a masterpiece IMHO. Credit for the Mac goes to Xerox PARC and to Engelbart's lab at Stanford Research Institute, but also to Jobs for recognizing the value of the work and leading the first implementation of it available to a large fraction of the population.