You can install debian and ubuntu with same DE and you'd be hard pressed to find a difference apart from the theme unless you are a power user who knows what snap is.
In fact, Ubuntu has never been an especially user friendly distro. At the beginning it was just a debian that was installed with debian's experimental installer before they decided to use it in stable. Nothing more, nothing less.
If you wanted to find a distro that was making efforts towards beginners looking for Gui config tools, you had to look at Suse and Mandrake (now Mandriva).
The only specific thing Ubuntu did for beginners is sending CDs for free at a time when not everybody had fast internet connections and would look for paper magazine to come with CD/DVD. And they have stopped doing that a loooooong time ago.
Or unless the capacity of you harddisk is limited, filling up with huge snap packages.
Or you need something that is broken by snap. I helped a user after thunderbird after an upgrade could no longer open PDF-s in okular. It turned out that the thunderbird dpkg had been replaced with a snap and I spent quite some time trying getting it to work, filed bug reports, etc, before giving up and installing from Mozilla until I replace it all with Debian.
>The only specific thing Ubuntu did for beginners is sending CDs for free
Assuming you are not malicious I will kindly help with your bad memory, Ubuntu had always very good proprietary driver support, this made laptops actually work and helped beginners. I also remember they had a graphical installer compared to Debian and for sure this was beginners friendly. Maybe some other distro offered easy way to install and come with proprietary drivers setup but I can't remember a deb based distro doing that.
Anyway you were wrong, the CDs were not the only thing made Ubuntu appeal for beginners, there were Linux magazines with CDs each month and they were not super expensive , my first linux was a Kubuntu 6.10 from a magazine and I am still running Kubuntu today though i ran Debian, Sidux, Arch, Mandriva, SUSE in the past when I had time to try different distros, compile custom kernels etc.