Coming from the other side of things, I had a lot of trouble when I was lent a brand new Macbook Pro for travel during my last job. It seemed some things worked using cmd and others using ctrl. I don't remember the specifics, as I didn't use it often enough, except that I'd find myself mashing keys on occasion trying to figure out the right combination.
It was far worse when I dual booted with ubuntu. The keys made no sense to me there either. Finally, I replaced OSX completely and the keys were "normal" again (ctrl+* for everything).
1: Also lots of DOS, but I don't even remember what versions. I had managed lots of desktops and servers running DOS for a few years in IT a couple lifetimes ago.
IBM CUA and Microsoft Windows adopted them afterwards, adapted to the PC keyboard; I think Windows only adopted them with Windows 95 and NT4.
Even on OSX, the bindings that are used are cmd-c and cmd-v. It is universal - if you have never used the terminal, vim and firefox on a mac... I really urge you to do that.
you'll see what i mean.