Major: Debian, Gentoo, NixOS, Arch and also FreeBSD (not GNU/Linux but still).
Other and esoteric: Void, Alpine, Solus, CRUX, Slackware, Mageia/OpenMandriva,
Corporate sponsored: Fedora, openSUSE
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
Major: Debian, Gentoo, NixOS, Arch and also FreeBSD (not GNU/Linux but still).
Other and esoteric: Void, Alpine, Solus, CRUX, Slackware, Mageia/OpenMandriva,
Corporate sponsored: Fedora, openSUSE
If you use a standard package-manager-based taxonomy, there are five base distributions: Slackware, Debian, Red Hat/Fedora/CentOS (I'm unclear on which of those is currently the lowest rung), Arch, and Gentoo. There are also a handful of singletons, like Puppy and Void, which evolved independently (or from long-dead predecessors) but have no family to speak of. I think the only one of those that isn't community-driven is Red Hat.
However, most base distributions are set up because their founder wants to try Something Completely Different, and that "something" is generally not user-friendliness. Even in Debian's case, the core distro philosophy is about software licenses; its user-friendliness is almost a historical accident. Descendant distributions with a premise of "[distro], but user friendly" are not uncommon, though.
Linux Mint Debian Edition (LMDE). All the benefits of Linux Mint, powered by Debian.
I feel like posting that I was there 3000 years ago meme lol.
I remember when the roots of those family trees where new.
In my opinion, the only "root distro" which ticks all your boxes is Debian, especially with the advent of Debian 12.
All the other distros are too opinionated to be "user friendly", except maybe Solus which I've never tried.
From what I remember, AOSC OS is fairly easy to install, though it's more niche, so I don't know if I'd recommend it to a new user. There's also Solus, I suppose, but while there is a new release out, I wouldn't count on it remaining actively supported, given its track record. OpenMandriva and Mageia are worth noting, too. Their parent distro was corporate, but it doesn't matter since its dead now. Not a lot else I can think of.
I used to use Mandrake back in the day. Those Mandrake descendants, as long as they're actively being maintained, could be interesting.
For all the shit Red Hat has gotten, Fedora Linux is still actually a community base distro.
Linux Mint Debian Edition (LMDE). All the benefits of Linux Mint, powered by Debian.
Slackware / opensuse
The problem with OpenSuse is it's based on a corporate product, not an original community base.
Ok but not Slackware (the base of opensuse), gecko, puppy or other versions.
Solus deserves to be mentioned here, it's a great distro. The project went through some turbulence earlier this year but seems to be back on track as they've just released a new .iso.
OpenSUSE
inb4 but thats a corporate distro, it is just sponsored by SUSE but is community maintained
I agree that there are not many distros that are both user friendly and not forks of something else, but I don't see it as an issue, imo there is nothing wrong with forks.
The issue isn't if something is a fork or not, the issue is if something is a fork of a corporate distro. For instance, there are forks of Arch that still meet the criteria because Arch is a base community distro, whereas OpenSuse is a fork of a corporate distro.
OpenSUSE is not a fork. It's the base.
Most community distros are small and based on something else; and that's kinda the point. They're not trying to be next big thing, it's just a bunch of people with a common vision that come together to achieve what they need.
Debian and Arch are the exception, and, other than them, the only community distro that isn't based on anything else that I can think of is Mageia.
Edit: OK, I forgot about Solus and Gentoo, but Solus is a zombie at the moment, and op asked for something easy.
I don't mind adding forks to the list, or distros based on other distros, as long as the distro they're based on is a community distro and not a corporate distro. Like you point out though, there aren't a lot of those.