People, who want to learn something, often ask themselves, why is something supposed to be difficult, like playing piano.
From the point of view of someone, who isn’t even a beginner, a thing could look easy. You have got notes on a sheet, so you have to learn notes. And you have keys on a keyboard, so you have to find the keys and associate them with the notes on a sheet. Then you have to memorize the notes and practice by repeating and repeating until you know where the keys are, withouth thinking, because that would prevent playing fluently.
I could say, I now know the right keys on the keyboard and I know when to play them. Actually from the point of view above I should be able to play the piece.
The other thing ist … It’s getting clearer and clearer where the real difficulties are. It’s the dynamics, it’s the change in dynamics, it’s the perfect timing, it’s about emotions and so on …
The beginners point of view is: Ohh … I will never learn this … can’t do …
The basics can be learned fast, but then you get to a point, from which it’s a lot harder to progress further …
Whatever, I didn’t manage to play 3/4 of River flows in you without problems in timing and dynamics … Still, the last 1/4 has to be learned by heart …