C is the language used to program the homebrew and compile it to binary format to be run on the console.
Python is used for tools to launch on a computer. It could have been .exe instead of .py, but it would have work only on windows, and you'd needed to compile the sources using a compiler (Visual basic, etc.), but again each computer don't have the same compatibility (VCredist missing, library, dll, 32bit, 64bit, etc. etc.)
so many headheack, just to get "heyyy, I'm on Mac, please how do I compile?"
Using Python is a multi plateform tool solution (not the actual homebrew on console) without the need to compile.
The link you gave are just individual programs you can use if you want.
For the first wiiU homebrew, it was needed to compile homebrew and inject them into a payload exploit. It could have been anything else, java, exe, etc. python is usually chosen for its ease of use.