Mmmm well I used to work as an IT instructor - and from a generation that had grown up using computers most were unaware of the basics. And indeed on one level why should they know them, after all as long as they can do what they need to do why should they know all the ins and outs. Having said that the level of ignorance extended to not knowing what an operating system was and what an application was. This stems from most of them having everything bundled with the machine when they buy it.
It also extended to not knowing what a web browser was or what a word processor was. They knew that you could surf the internet with Internet Explorer and they knew you could use Word to write letters with. One of the qualifications I taught was the European Computer Driving License, which was supposedly software/OS neutral. It did include a module on the basics of computing, ie what hardware is, what software is, what is an application and what is an Operating system. Many found this one of the hardest modules - as it dealt with concepts rather than a sequence of key presses. The module on file types and file organisation was also difficult for many.
As to computer interfaces, well there is little choice there, going back to early GUIs like GEM you see icons and file managers - ok no start button but that came later. Once certain paradigms are set its difficult to move away. All GUIs live in a common ecosystem as it were, so all will be influenced by each other. With Linux we have the luxury of choice, so my preferred gui is IceWM, which I have got to look the way I like, and is nice and lightweight. Others like XFCE or KDE or GNOME etc, but most seem to have a menu button, ok flux and WindowMaker don't but they then all have a click on the desktop to bring up a list of programs. So even without the menu button they have the same functionality.
In reality it takes little time to learn to use any desktop. OK the programs will have obscure names (Gimp, Access, Xine, Excel etc) but usually you can find out what they do by launching them... so a little exploring can go a long way.
Of course tutorials etc are good, here I will mention the multimedia bonus disk which comes with a nice manual that can get you started with some of the applications.
It would be nice if there was a link/icon that lead to simple tutorial videos for people, but this is something that I think is beyond the scope of Vector as present constituted. Though a nice side project for someone. And certainly I'd be against putting them on the CD (though on a bonus cd for paid for versions might be an idea), a link to a website would be good.