What is the correct hand position for playing piano?

According to instruction captured in a piano lesson transcript, proper hand position at the piano is described as follows:

• Rest your hands on your knees naturally, then lift them — this creates a natural rounded shape with a small bubble or curve in the palm.
• Gently place your hands on the keys in that same rounded shape.
• The first joint of each finger should curve in slightly, maintaining that bubble on every finger.
• Your wrist and arm should be level — like an even walkway, not a slide (where the wrist droops).
• Keep shoulders relaxed — do not raise them to lift your arms.
• Play on the fleshy part of the fingertip, not the very tip or flat of the finger.