People talk about "learning Ubuntu". It seems simple enough to navigate the desktop to me. What am I missing , because I love to learn new things?

I think you are doing the learning right now. There are a lot of preconceived notions that Linux is this very difficult thing to learn. That it's all command line and no fun ever. But modern Linux is just as user friendly (even more so I think but that could just be the rose colored glasses) as any other operating system.
If you want to learn you should focus on the command line and all the power it unlocks for you.
Start making changes to configuration files through the terminal (these are the . files in your home directory) with vim or nano. Use find, ls, top to discover your system. Learn to troubleshoot issues through the terminal