Hue also makes sense. It's the distribution of wavelengths being reflected.
But what does saturation correspond to? When do things become saturated/desaturated in the natural world?
This means that the signal getting to our brains is actually a report of "how much {(red minus green), (yellow minus blue)} relative intensity" there is in view.
Saturation is our name for the feeling of having strong visual qualia, brought about by the magnitude of one or both of the relative-intensity signals being large.
• This is why oversaturated bright colours can trigger migraines in people—they're the strongest encoded signals, causing the most synaptic firing.
• This is also why some oversaturated colours don't seem as "bright" as others—you can make a "Brown 2.0" that's ultra-mega-brown, but it can't be as intense in {R-G, Y-B} terms as the pinkest pink (https://culturehustle.com/products/pink-50g-powdered-paint-b...), since pink/magenta is a full relative intensity pin {1-0, 0-1}.
• This is also why staring at oversaturated colours for long periods leaves more of a visual afterimage than staring at equally-bright white does. It's the {R-G, Y-B} intensity, not the brightness, that's using up the electrochemical messenger molecules in your retina.
https://www.rapidtables.com/convert/color/rgb-to-hsv.html
I suspect a lot of natural stripe patterns require saturation to distinguish them.