Four notes of that Ground BGM and your brain is already running through World 1-1. Koji Kondo wrote the Super Mario Bros. soundtrack in 1985 with two pulse channels, a triangle wave, and a noise channel, and somehow invented the template for every platformer score that followed.
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The Underground BGM drops to a chromatic bass figure that immediately tells you the rules changed. Castle BGM is pure tension, just minor intervals and staccato rhythm creating dread from almost nothing. The Hurry Up variants add urgency by just bumping tempo, which is so simple it's kind of genius.
That Underwater waltz proved the NES could do graceful. Nineteen tracks total, most under thirty seconds, every single one permanently lodged in culture. If you think you know this soundtrack, listen to it isolated from the game and hear how much Kondo built from so little.