I switched my computer illiterate family members to reduce the effort of helping them and they didn't notice.

As a helper..

There are distributions focussed on the latest and greatest (Arch, Fedora, etc..) and ones aiming for stability (Debian, Ubuntu, etc..). Think of them as groups with different views.

So Linux Mint is Ubuntu but it has the latest Cinnamon desktop. Ubuntu is Debian but focused on fixed releases and adds 'snaps' and includes "non-free" by default.

People have different views on how the desktop should work. The two big desktops are Gnome and KDE.

Gnome is like Marmite. Its works completely different to any other desktop and people either love it or loathe it. Its often the distribution default.

With Windows 10/11 I think Microsoft were trying to steal some of KDE's best features. By default it looks very much like a Windows desktop but lots of people mod it to look/act like macos. Some people struggle with the options it provides.

Then there are lots of other desktops, for example Cinnamon takes Gnome and turns it into a normal desktop.

Personally I would suggest Kubuntu as your first attempt. This is a fairly decent install guide.

Ubuntu tries to minimise the choices you need to make and the 6 month update cycle keeps it fairly stable.

Kubuntu is Ubuntu it just makes KDE the default instead of Gnome.