That does actually still pass by one factor that you have to address.
The folks that actually know and interact with mana are a minority on a massive scale, and unlike physics, which we all passively interact with, the only time mana comes into play as a phenomenon is when acted upon by an outside force.
The amount of people that, thereby experience, some of these supposed constants are (generously) about .001% of the population while the rest experience reality pretty much as we do.
It's not a refutation of your thesis, but does require an answer.
People do actually interact with mana. All life absorbs mana, but those that utilize that mana as spells are indeed less than .001% of the population. Furthermore, angels, demons, elementals, and horrors are generated-most of them spontaneously-through ambient mana. While it is true the grand majority of any species do not interact with mana as much as physics, the mana present on any plane does have a cause and effect on reality that most people do not see or care about for that matter. Just as a kid wouldn't care why the sky is blue, people in the MTG verse wouldn't care why elementals are created.