Just to clarify, it’s not *quite* like that. It all started with an operating system called “UNIX”, which was designed to run large networks and supercomputers. Both Apple’s OSX and Linux are in effect, versions of UNIX. Apple’s is a “private” version that they wrote just to run on their hardware (although you can, with difficulty, run it on other systems) and Linux is a version designed to run on virtually anything.
The big bonus with Linux is that it’s generally free to download and you get access to a HUGE library of software like word processors, graphics programs, sound editing and so on. All (legally) free.
The downside, as you say, is that it’s considered a bit of a “difficult” operating system. That’s not entirely true, I’ve set up a special version of Linux for an older relative that simply has big “Email”, “Internet” and “Word Processor” buttons and very little else, it’s far simpler than Windows or Apple OSX. The “normal” versions are very similar to Windows and OSX these days.
The other confusion with Linux is that there’s so many “distros”…because anyone is allowed to set up their own version of Linux there are lots of different ones. Ubuntu, Fedora, Red Hat, Gentoo, Mint….they’re all basically the same thing but with a different “look and feel”. Ubuntu (in my opinion) is particularly friendly for beginners if you want to try it.