I have no idea what the rustle was.

I feel like that was quite key to the whole bit, but who knows.

Think of it as a commentary on colonialism - the more advanced newcomers think nothing of wiping out the natives, believing themselves to be inherently superior to them, and thereby proving that they’re not in fact superior - they’re just brutes with better weapons.

While I’m not sure that is indeed what it was going for and feels like giving it more credit than it should have, I do like this interpretation.