Try playing on the easiest difficulty and fighting slowly. It's just like riding a bike. You have to start slowly. By slowly stringing together attacks, you will master them within an hour, then add a little more, then a little more, and eventually, by the end of the game, you'll be slaying demons in style with consistent SSS tier. Then, you'll want to further test yourself on normal, and through that progression of skill, you'll eventually be flying around like you see other people do.

Trust me on this. This is not only the deepest action game ever made, but also the most accessible. If you start small and slowly try more and more, you will get good at it.

Except Dante. I've put a ton of hours into this series and I still haven't even gotten close to mastering Dante. Nero is a great character for beginners.