GNOME? It is super simple. I have used Fedora/GNOME on my elderly family members laptops for many years now, and they just get it. Even the ones who came from Windows 10. The hours I spend on support has dropped significantly. Windows is such a hassel, and its desktop design philosophy is just not that great for casual users.
IMHO, GNOME is not simple, it's dumbed down. They've obviously tried to copy Apple where it suited them, but missed on a whole bunch of important details, like a unified menu system, a powerful terminal emulator, desktop icons (omg), while badly aping all of the worst parts - from requiring 4 clicks to shutdown/reboot (where macOS requires 2), thru a mostly useless top bar that steals the real estate from browser tabs (Fitt's law), to asking SDL to link against libadwaita to draw window decorations. And this is the worst part, they not only do not want to accommodate their users, but also ignore the developers - those who wish to integrate with and therefore empower the free desktop ecosystem.
Apple can get away with all of that because they're a trillion dollar company, but unlike Apple, the power of the open source community doesn't stem from an unimaginable pile of cash, but from interoperability and cooperation.
I tried to use GNOME for about 8 months but there was just too many WTF moments (one caused by Ubuntu's own dock extension). There's plenty to love about GNOME but missing features, bugs, and design/usability issues makes it feel like beta quality software.
A few months ago, someone wrote a blog post[1] cataloguing many of these issues. One thing not mentioned was the lack of a caps/num lock on-screen indicator, this is a feature that is present in GNOME 2, MATE, XFCE, Cinnamon, KDE, and Windows 7/8/10/11 out of the box and toggleable in their settings window. The only way to gain this functionality in GNOME is through a third-party extension. Many laptops continue to be manufactured without a caps/num lock indicator on their keyboard, it's insane this isn't a supported feature in GNOME.
I don't get the feeling that GNOME team has ever implemented accessibility research in their design choices. For those with disabilities, GNOME is unnecessarily difficult to use [2][3].
So far, my experience with people above 60 is that they quickly understand how to find and navigate between the apps they use every day. The ones coming from Windows adapt suprisingly fast, and are very pleased that the fullscreen popups and forced updates are gone. Shortly before I moved them over to Fedora, they started developing a fear of using the computer because they never knew when it would 'lock them out' because the screen was filled with a fullscreen Office365 ad that had no obvious exit button.