In a linear model, mass can be seen as a resistance to a force.
F = ma or acceleration = Force / mass
But physics tends to ignore the other motions. Ignore the non-euclidan geometry. And in some of those, Newton doesn't hold up.
An example is that E-M drive that guy thought up. A microwave horn into a specifically designed cone, and it makes a force where there is no equal and opposite force.
All my stuff is in storage :-( But, the secret space program has flying saucers that work off similar mechanics.
Yes. We simplifty things. I use Euclidean geometry for distances within a city because it is approximately correct but between continents the error becomes too large.
The modern physics world also ignores spin, counter-spin and frequency (as it defines distances and patterns)