Agreed.Someone totally new to chess really doesn't need to memorize any openings.What would be useful would be to look at a few openings and understand why the moves that are played are good. I'm very new to chess myself and only rated about 1100. I have a good unserstanding of opening principles now and I do have a few openings memorozed about 10-12 moves deep for white and black, but at my level the book moves often don't even get that far.
So as "I am second said" opening principles first. It would be useful to know how to defend the common checkmate traps, especially those that attack f7.
It all boils down to your style. If good moves don't seem natural to you in the transition from opening to middlegame then you might want a new opening.
Like how wearing clothes seems to not match the wearer sometimes (like rich white kids dressing "gangster") the opening must fit you. Don't worry about preparing against a specific opponent. Yes they may do poorly against the Caro-Kahn, but you might handle it poorly and therefore give them the full point.
"What you need to teach them is the opening principles:
1. Control the center - e4-d4-e5-d5
2. Develop your minor pieces toward the center
3. Castle
4. Connect the rooks - move the queen"
I largely agree with this but some openings like the Fried Liver seem to throw it out the window so calculation matters too. It's better not to enter such positions however and 3...Bc5 I'd recommend (like everyone did)