The whole point is that you're supposed to find vulnerabilities in what you have access to and exploit them to view contents of things you don't have permission to.
I replaced the date with my own script, but it still gets executed as level01 user
Hint: not all shells blindly run scripts as the setuid user.
HINT: For the purpose of this hint we'll assume your script is a bash script. If you've exploited the setuid program to run your script, bash may execute with the elevated permissions, but any program bash runs will run with your permissions.