>>1591990
It's quite simple if you want it to be simple.
< Pick a distro
This is the hardest part, but it's not really hard. As long as you go with any of the mainstream distros you will be fine. You can change your distro later, so dont' worry too much about it. Avoid meme distros. Anything Ubuntu-based is a good starting point. Your packages will be outdated though, but that's by design.
Debian and Ubuntu (which is based on Debian) are considered "stable" distros. Stable in this context does not mean that it does not have bugs, just that the underlying system won't change under your ass all of the sudden. The distro maintainers will backport security fixes, so being outdated is not a security issue, it just means you won't get any new features until a major OS updated. This is very valuable on servers, not so much on a workstation. The main advantage of Ubuntu is that there is a lot of information for beginners out there.
Fedora is a good second choice if you want more up to data packages. It is a different distro from Ubuntu/Debian, so things will be a bit different. It's a good second distro though.
Arch is also a fine jumping off point if you are willing to invest more time an learn stuff. It's like jumping into the deep end of the pool. There is a lot of information out there on Arch, but if you want a distro that just works pick one of the two above.
< Pick your desktop environment
There is endless potential for autism, but if you want something that just works pick one of the popular ones. My personal vote goes for KDE Plasma, it's very customizable if you want it, but it's also great out of the box. GNOME is very popular, but I cannot stand most of its UI decisions.
Don't worry about the DE, you can always install a different one and switch between them. Unlike a distro you are not locked into your choice.
< Install it
You will need to download and image and flash it onto a USB drive. I don't know how to do it on Windows, so you'll have to find instructions somewhere else. Insert the USB drive, boot from it and play around with the desktop a bit, try out if everything works. Once you are satisfied you can start the installer. Aside from Arch all of the above distros have GUI installers, so if you can install Windows you will be fine.
< Just use it
Don't overthink it. Just use your computer for everyday tasks, install some software, try things out. You will probably want to look into FlatPak as a secondary app store for stuff that's not in the distro's package repositories.
< Gaming
There are launchers like Lutris or Heroic. I don't use them, I use plain Wine and DOSBox, but other people seem to like them.