How about Twinkle Twinkle Little Star? You don't even need an instrument. And it's bookoo years old, and the tune is actually an old French folk song "Ah, Vous Disrais-Je Maman" so there's your folk roots. And everyone knows it. And you can't accuse it of being a project or contrived or insincere or pop or noisy or electric or new or nonsensical or stupid or boring or whiny or derivative or emotionless.