Wow, I strongly feel the opposite about C. It is hardly simple or clear - understanding what your code will do after the compiler's done with it seems almost impossible, reasoning about runtime behavior similarly so. The complexity involved in managing memory, etc, is so significant.
But it is extremely powerful.
I see go as being extremely simple, but also very weak in terms for expressiveness, relying on the runtime for memory and concurrency management.
I agree that Rust has more in common with C++.
I describe C as "simple" in the sense that it's A) not a large language, by specification and B) somewhat by virtue of the former, there's generally a small range of possible implementations of any given problem (which helps C programs have "clarity"). Go is very C-like in that it also has both of these attributes, quite deliberately. C could be considered complex, however, by virtue of the amount of behavior that is unspecified/at the compiler's discretion. In that sense its safety often is difficult to reason about, but C programs themselves are generally easy to reason about. Go luckily doesn't have many opportunities for programs to be "complex" in that way.
C is "powerful" in the sense that it offers programmers deep control over memory. Given that, (effectively) anything that can be implemented in any other language can be implemented in C, with varying levels of difficulty. It isn't "powerful" from the language perspective itself — in terms of expressiveness or the features that it affords programmers — in the same way that C++ or Rust are "powerful".
A lot of the adjectives we use to describe languages aren't particularly well-defined, so some disagreement about them is almost a given. But hopefully that clarifies.