Yes you shouldNt have been able to teach it till you had used it at least once , For real,I was a CPR instructor for quite a few years. Never had to perform it other than on a mannequin. Does that mean I shouldn’t have taught the class?
I had two students successfully use the skills I taught them afterwards.
Edit: I’ve also had people in my class who’ve performed CPR before taking my class - recertifying lifeguards, EMS, etc.