I prefer the UI of Shotcut, but kdenlive is admittedly more powerful. You can try both to see which one you prefer. I suggest you download the .appimage files of both of them from the website (this way you’ll get the latest versions). I’d suggest against the flatpak versions as sometimes they come with limitations of various kinds. Just download their respective .appimage files, make them executable (right click on the downloaded files with your file manager and then go to their Properties to set them as executable), and then double click them to load. If you go that route, make sure you manually update them every 3 months or so, as that’s when they usually release updates.
Step 1: Use a youtube tutorial for the basic commands. Don’t worry, you’ll forget about them soon enough. But doing them once, helps with muscle memory. Step 2: When in need to do something, copy/paste from Q&A/forums various commands that they suggest for your problem. Your basic knowledge from step1 will come back as you do that.
After a few days, you’ll be understanding what’s going on and how the whole thing works in an abstract level.