Some piano beginners and intermediate learners have a tendency not to lift your fingers up from the keys. They like to be touching the keys all the time. Then, when it is time to strike a key, they strike it from where the finger is already touching, basically from the surface of the key. When I advise my students to lift there fingers, many say that they are worried that they lose the hand position.
Let me give you an example. When you strike a nail into a piece of wood with a hammer, how do you strike it? Would you strike it from where the hammer touches the nail? Of course not. That's not possible. If you do that, you can imagine the nail is not going into the wood. To strike a nail, you have to move the hammer away from the nail first. Then, you strike it. If the nail is big and you want to put it in deeply, you probably move the hammer even farther away from the nail. If it's a small nail that can easily go in, then, you strike it from very close to the nail. But it still needs to be off the nail a little.
The same applies to piano playing - pressing a piano key with your finger. Unless you create some kind of space between your finger and the key, you are not leveraging the space and the energy that can be created by the space. You can use that space to create all kinds of tones, loud, soft, gentle, warm, harsh, sharp, etc. So, I advise all piano players to get into the habit of lifting your fingers that are not yet striking the keys, off the surface of keys, especially before you hit the keys.
The best way to make this a habit, it's a good idea for all the fingers that you are not using at the moment to be above the black keys, not just above the white keys. I usually give a visualization like this; You can think of your fingers as either clouds or airplane flying high in the sky; The black keys are like mountains; The white keys are like a city or the ocean; Your fingers are like a passenger in the airplane looking down the mountains and city. Then, when you have to strike a key, a raindrop (your finger) will either drop on a black key or white key straight down. You don't have to press the key hard because no matter what, if you let go your finger, the gravity will pull it down. But when it is going down, you have many different choices; how high you want to drop from, how fast you want to drop, how gentle and wavy you want the drop-motion to be, and so forth. Depending on how you use the space for your finger to drop down, you can create different kinds of tones that you are looking for. This is why the space between your fingers and keys is so valuable.
Have you been afraid of lifting your fingers off the keys? Then, experiment with the use of the space between the keys and your fingers. You'll be surprised to see how the piano responds to how you use the space.