Indeed, the entirety of Western music theory exists first and foremost in the context of Western common practice period ("classical") music. The further you diverge from that specific context, the more trouble you jave trying to make the abstraction fit the music.

What are you calling "the entirety of Western music theory"?

At base - chords, scales, keys - it all relates back to fifths, the most harmonic interval. That's based on physics, not Western classical music.

Chords, scales, and keys are all Western concepts. You might want to study some non-Western music traditions, in many of which harmony plays little role. Or even Western ones not based on quintal harmony, like a lot of jazz, not to mention all the experimentation in atonality in 20th century Western art music.

All languages ultimately relate to the way humans produce sound. That does not mean that English linguistics is tremendously useful in analyzing Japanese, even if it's better than nothing.

Sorry - scales are a western concept?

We have bone flutes with pentatonic tuning that are ~50 thousand years old. We have written records of scales, including major and minor, that are older than Ancient Greece.

And if scales are that old, then so are keys, and so are chords; no?

Isn't the old joke...

A young banjo player asks to jam with the old timers at the sawmill. Sure, they say, and invite him in. As they play for awhile, the youngun asks the elder picker, "Say, old man, can you even read music?" to which the elder replies, "Not enough to ruin my playin'"