Playing the piano is like walking in the sense that you are transferring weight from leg to leg and ultimately from foot to foot, which is very similar to playing the piano, with each hand simulating what we do when we walk. In this case five fingers is like using five feet except instead of transferring the whole body weight we transfer the arm weight from finger to finger.
So we need to execute a balancing act. The hands need to acquire a curved shape like holding a ball and the wrists and arms rest by your sides with the arm weight pushing down on the keys of the piano, which has it’s counter-weight like a teeter totter, while keeping the wrists straight with no arch. So when it comes time to playing different notes with different fingers it is not like getting the fingers to be hammers but more like letting the fingers support the weight of the arm and behaving like our legs do for walking.
But in a very similar way to dancing the notes need to be played with a logical sequence of fingers as in dance steps. I think of Fred Astaire as the ultimate in cool as a dancer with great skill. Much of his style was dependent on his ability to relax. It’s the key to speed and endurance. Marching takes more energy than walking and we want to conserve energy so we don’t get tired or develop carpal tunnel for those who insist on regular practice the wrong way. It’s Like Learning to Dance