Are there Krita Tutorials/Courses? Yes. If you want to learn about the program, the shortest way is through a course, as I said in this other topic. I took my course on Udemy.
As for the other questions, the problem is not the program or the animation style. The basic principles and techniques of animation were developed in the first half of the last century. Even 3D animation follows these principles.
You can see this topic, where I made an animation in Krita, following a tutorial that was for another program. Today I would make that animation in Krita in a different way, because I learned more…
Here are some links that may be useful:
How To Animate in Krita for Beginners (2023)
Various animation tutorials
The Twelve Principles of Animation