Once you have the idea, seeing that it works if often easy. But coming up with ideas like that can be really hard, which is why gauss was the only one in his class who got it. There is no general method, you just have to think about stuff for a while, but you can get better with practice. And it feels really good when you prove something for yourself, even if it’s relatively straightforward. You can just try to prove some simple things yourself, if you want, the advanced college courses are just for proving really advanced stuff.
In your case I would just start by copying a full setup someone else made and then customizing it, starting from scratch always takes a lot of effort. Reddit’s unixporn was great for that, the alternatives on lemmy are sadly still a little empty.
Someone needs to maintain them for them to keep working. Nobody else is willing to do that anymore, but you can still volunteer as a maintainer. If you don’t, it’s as much your fault as anyone elses.
Linux by itself is just a kernel, there’s a whole range of operating systems using it. Most of them have some commonalities, but there are also huge differences. Most of them can run directly from a USB stick (or in a VM obviously), so you can try some out.
Some things that basically all of them do very well, compared to windows:
mainly open source components (± some proprietary drivers and apps, if you want)
no ads in the OS
support for very old hardware, being (depending on actual OS more or less) light and resource efficient
very good package management
customizability
There are many things that are specific to some OSes. I switched from Windows 10 years ago, and I can’t see myself going back. Everytime I have to use it somewhere, I get annoyed quickly.
There are some drawbacks:
software has to be built against a specific kernel, and some proprietary software is not offered for linux. There are compatability layers for running windows software on linux without emulation, but they are mainly optimized for games (I’ve had windows-only games run faster on linux than on windows!).
some drivers are unavailable for linux, as the device manufacturers have to cooperate somewhat. However, almost everything will work.
some drivers are available, but require binary blobs distributed by the manufacturer. The proprierary NVidia drivers, for example, are faster than the open source reimplementation noveau, but they can cause problems with some software like sway. If you have an AMD gpu, their open source drivers are great, so no problems.
Roughly all the servers (including Microsofts own cloud), half the mobile systems, lots of the larger embedded stuff and some small percentage of deksktop systems are using Linux. Again, just try something (maybe Pop!_OS or Mint) and see if you like it.