It's also physics, those notes sound good next to each other because mathematically their frequencies are resonant (simple relationships like 3/2 or 5/4 as opposed to, say, 729/512 of a tritone).
I'm not saying that it's not awesome that this scale is still in use (it is) or that hearing that flute doesn't make me emotional (it does), just noting that there is a reason why.
Still, it seems very likely those Neanderthals 60k years ago were playing music for all the same reasons we do, even making efforts to understand the principles enough to make clever instruments.
Maybe the Neanderthals even knew about such ratios. It's discoverable by playing with string, or even plants.
By then, one is off and running with developing a workable flute.
Alternate ending: "suddenly jazz appears"
If you stack fifths on top of each other you also get the major pentatonic scale, like going from noon to 4 o’clock on the circle of fifths.
If you keep going around you basically spell out the major scale, other than the sharp 4, and this is the foundation of Russell’s Lydian chromatic scale.
The 5/3 ration of the fifth note (A in the C major pentatonic scale) is already evidence that there is some kind of stacked tonality.
So yes, it is still physics, but there is definitely a level of complexity above just simple ratios against a root note!
You can take the harmonic series farther up, specifically in the range between the 8th and 16th overtones, and get a scale that is very close to containing the major pentatonic, close to a C7#4, but it sounds a little off outside of equal temperament!