What should I do to understand complicated artistic concepts better?

It depends on what you're trying to achieve. When friends want to get into drawing/digital art/painting, I try to tell them to practice drawing from life. Still life, photos, yourself in a mirror. Learning how anatomy works in the real world is key to understanding how it can work in a more cartoon style, if that's what you'd like to go for. I also tell beginners that copying is fine, as long as you're not trying to pass it off as original work. Find an artist whose style you admire and would like to emulate, and the more people you want to emulate the better, and try to eyeball pieces of theirs that you enjoy, to get a feel for how they may have done it. Combine the aspects of the styles that you particularly like. It might not look good in the beginning, but as you go and improve, it gets better.

Use references! My art looked like garbage when I was trying to pull everything out of memory. As you reference things more, if it's a common theme in your art you may not need as much reference anymore, but until then references will help you so much! Any time I come across an image online and I think "oh I love the fold in that cloth at his elbow" or "wow that's a cool angle on that animal's face" or "that is amazing lighting reference" I save it. I have so many reference folders across so many devices! And it's the same for color schemes. Familiarize yourself with the color wheel and he ways colors can be combined, and with concepts like tint and hue, but if you have a hard time with it in the beginning there's no shame in mimicking the color pallets of other artists to learn how it works.

Just take it one step at a time. Sketching is a good place to start, then you can dip you toes into whatever type of art you think you might be interested in! It's best not to overthink it. We all start from square one.