Apart from actual system administration or kernel developing, there's no real "learn Linux" .
Video/Photo/Vector editing on Linux is not "learning Linux", it's learning to use a tool which runs on Linux. You can learn to use Blender, Gimp or Inkscape on Windows. You don't edit videos/photos/vectors with the Linux kernel. You can even "learn the linux terminal" installing bash on Windows.
You can also install Visual Code or IDLE on Windows and on Linux. Learning to code on Visual Code or IDLE is not really "learning Linux".
Also going on distro hopping looking for the "perfect distro" many times means the hopper simply doesn't stick to one long enough to learn how to customize the environment to their liking (which usually means the window manager).
Most of the things you can do on the GUI, even the administration ones are just layers and layers of tools to make things "easier" - and they'll be different on each distro and release. Command line administration will change much less, or at least less frequently.
Things I consider "learning Linux" are for example:
-
installing Linux (specially a headless server)
-
understanding how to use the package managers - again, on the command line
-
understand how systemd works
-
(hard core) dive into the kernel workings
-
understand how grub works
-
learn the general filesystem structure
-
learn how to analyze logs
-
learn user administration and how the permissions (and extended permissions) work
-
learn how to integrate Linux to a Windows environment (join a workgroup or domain, share storage, authenticate users)
-
learn how to check resources usage and how to troubleshoot it
-
understand the nuances and of partitioning and when they are needed, as well as the different filesystems
-
etc (and /etc)
And yes, many of those are not strictly "Linux", but are specific to a Linux system, unlike photo editing.
I like that I don't even care about it. The main user of it is my wife, who is non-technical. It's the only computer she uses, for everything (browsing, shopping, banking, word processing, printing) for 20+ years, and if you ask her which distro it is, well, she doesn't know what "distro" means.
She doesn't "use Linux" because she wanted to "learn Linux" nor to "try this distro". She uses youtube, instagram, the bank site, amazon, libreoffice, etc. The closest she gets to the OS is accepting the package manager prompt to update.
I wish one day most people can answer your question with "I don't know, whatever came with my computer", because it'll mean all of them are as easy to use, as unobtrusive and as unimportant to the user as possible.
But to finally answer it, kubuntu, some ancient, still updatable LTS version (can't even recall when I last upgraded), because it was easier for my wife to adapt, coming from windows 95 when she started using it.