C is a small language. People confuse simple with small quite often. As languages get smaller, using them gets more difficult once below a certain size. The "Turing tarpit" languages like Brainfuck are extremely difficult to write complex programs in, mostly because they're so small.

C is clearly too small to be simple. C++ is too large to be simple. Somewhere in between, there may exist a simple language waiting to be invented.

C is simple in the same way Conway's Game of Life is simple.

That's not to say you can't create interesting monstrocities out of it!