Git Bash
is the GNU bash shell. Try typing echo $BASH_VERSION
at the prompt.
Like any shell, it has some built-in commands (all of which should be available); other commands are executables you can invoke from the shell. If some of those commands happen to be missing, that's not an attribute of the shell; those commands just don't happen to be installed on your system.
What you're missing is that most of the command you invoke at a shell prompt are not part of the shell.