On distrowatch.com you can get an overview and search for a distribution.

Start trying out some with a live usb stick.

If you feel good with one, install it on disk and just jump into the cold water.

Most UIs like XFCE, KDE, Gnome, etc. are pretty easy to do first steps with.

How packages are handled on the distributions is one of the important differences which will influence your habits.

It'll benefit you to start using the command line (search for a "terminal" to open) instead to rely too heavily on graphical user interfaces. Most commands have a "manual page" which you can call with "man" followed by the cmd's name.

From there AI can help you along the way.

Have fun 😉