Adopt windows file system with letterer partitions as the root. Plus most people who use computers are used to this paradigm already. Who ever came up with Linux's file system has poor organization skills

My 90yo neighbor has run Mint since before I met him 15 years ago

Pls send me ur wallpaper (I fucking love stolas)

I think linux mint is already there.

I don't even know how could it be simplified more. It's really basic.

The only obstacle there is the previous familiarity with other operative systems that could make change bard. But I'm pretty sure that if you put anyone truly novice in tech in front of linux mint and windows 11, they'll have an easier time on linux mint.

Most of my family run Linux.

My parents run Linux Mint. It’s simple and looks like Windows. The only thing they need is a browser and LibreOffice.

Some other family members are using ElementaryOS.

The majority of PC users are IT illiterate. They have no idea what the difference between Windows and Linux is or the difference between Chrome and Firefox is.

“This icon is your browser. You know, where you can access the bank. And this icon lets you write documents”.

There was always issues when family members was running Windows. Haven’t had to fix anything after installing Linux instead. Some doesn’t even know they are using Linux. I just said I updated their PC 😅

I would make it controlled by voice. Just need to figure out a way to tell the user what the system can do. Computer, help me shop for medicin and hold up a box infront of the screen with what you use today. This should be simple. If you make it to complex like it is today then elder people will not use the computer.

Basically a personal assistent/guide driven OS. Start with rethink the experience you would have if you went to the mall and have a human assistent with a big screen to show you everything.

Auto update only critical and likely attack vectors (the kernel, network stack) and have them applied when shutting down, have visual hints that explain to them what each thing is and make it immutable.

a linux distro for extreme beginners in tech and elderly people

Android on a tablet.

I have both my parents on KDE with essentially the defaults. They came from Windows 7, so many things were familiar to them, like the systray in the bottom-right, the start-menu in the bottom-left and so on.

I mostly decided to go with KDE, because I use it myself. My dad can be extremely negative, so being able to tell him, nope, it works on my machine, often defuses the situation. But I also expected my parents to potentially want lots of little tweaks, which well, it didn't happen.
They use a browser and a printer, that's basically it. I have considered setting up an E-Mail client for my dad, and thought about setting up tiling window management for my mum, but done nothing so far. The OS could boot straight into Firefox and they would hardly notice.

As such, I'm definitely fine with how little problems they've had using KDE.
One time, I noticed my dad had a million tabs open in the file manager, because that got updated to remember open tabs, and something he did, would always open a new tab in there. Another time, he had managed to create a second panel, which sat at the top of the screen wasting space.
So, it would be somewhat nicer, if he couldn't do that stuff, but at the same time, it's not really a problem and I learned computers by dicking around, too, so I really don't feel like I want to lock that down somehow.

A dumb thing he did one time, which he could do independent of the desktop environment, is that he deleted all the folders in his home-directory. Intentionally. He has this habit of cleaning everything up, completely disregarding that he has like 99% free storage space. Again, he doesn't really use much beyond a web browser, and he didn't find out about hidden folders, so the only real effect was that his wallpaper disappeared.

I don't think that's the answer you wanted, but yeah, I would not want to lock them down to prevent this stuff from happening, unless it really becomes a problem.

For elderly people, an interface with options to have big icons and accessibility options would be very helpful; and accessing a program should take no longer than 4 clicks via mouse, or 6 keyboard keys.

GNOME interface succeeds well in that, as you can click Super key and be able to search between all the existing apps. Or the top left Applications menu could be used to browse through all programs.

For beginners in tech; GUIs for installing programs would be a big help. New people might see writing console commands for installing programs complicated, compared to other OS's show their app stores in a visible location. Also do not make users search for graphics drivers.

Mint/elementary are good if on windows 10/Mac respectively

What I would say is what is your reason for converting people, because you're going to end up as permanent tech support this way when they'd have probably been fine with a Mac or something

Why would it have to be KDE or XFCE? GNOME as it exists today is probably the closest to macOS' design language, and whatever you do designing any kind of operating system UI, macOS needs to be the benchmark. GNOME 2 in the olden days was my favorite DE so today I have to go for things like KDE or MATE but I'm not a novice and I can fully acknowledge that what works for me isn't what works for everyone. GNOME probably made the right decisions to lower the entry barrier towards Linux.

XFCE to me is purely a choice for outdated hardware so unless your extreme beginner has an extremely old PC XFCE is a non-starter. Whether KDE can be made more accessible to the non-initiated I can't say. Anything that has a Windows-esque taskbar is probably ill-equipped from the start as well. Again, macOS is as easy to use in a keyboard and mouse sense as tablets and smartphones are with our fingers. This is the way.

Wallpaper?

Isn't that Ubuntu?