Many adults come to the piano carrying a memory of being told, once, that they were not musical. That assessment was almost always about reading music rather than about music itself, and this tier begins somewhere else entirely.
You learn to sit properly, to find any note without counting up from the bottom, and to shape your hands so they stay relaxed. Then three chords, learned as shapes your hand remembers rather than notes on a page.
By the end of this tier you will play a simple song with both hands doing different things. That usually happens sooner than people expect, and it is the point at which the instrument stops feeling closed.