Re: YOU feel, old, I'm cattle-trucked then...
"I remember the 'joy' of using Windows 286...."
So did I. It came as a package from VisionWare which also included an Ethernet board with a BNC connector and an X-server which was, of course, the raison d'etre of the package. And on the other end of the net was an HP running HP Vue desktop which contributed to the subsequent CDE desktop.
Many of the ideas which went to W95 were in there*. Notably there was the start of the menu system but it was a bar with several pop-up menus. The major contribution of W95 was to condense these into a single button with cascading menus. As has been said elsewhere CUA principles were also followed - that's the File Edit etc menus. Those could be implemented in pure text as well as in GUI form.
What MS achieved was to combine a lot of what was already about in such a way that it hit a sweet spot. I've no idea whether this was good luck or good management but they did it. It offered some scope for refinement in implementation and a few features - auto-hide menu bars and multiple desktops for instance. But on the whole it was a feature set that was easier to bugger up than improve as a good many interface designers have proven in the last couple of decades.
*HP New Wave which was an interface revision dropped on top of W3.x also contributed to W95. It introduced the idea of an OO interface, namely that by clicking on a data file the OS would recognise the associated application and start that to open the file. And its text editor had a spill chucker. W95 copyright statements included HP along with the Regents of UCB.