we wouldn't be ((aren't)) accelerating towards the sun but in a vector tangential to the orbit. that vector ((relative to the sun)) changes relative to time - but because the radius of the orbit is large, the angular change over time is small ((relative to the earth's radial size & motion)), and it's below the level of our perception ((our perception is in fact molded by our constant experience)).
IOW you don't have a proof of flat tertiary topology. you have an observation about scale and about animal psychology.
this is actually a calculation we did in elementary physics 201 ((because it's not like you have some news flash that no one ever thinks of; it's well-known & elementary among anyone educated in physics)). to counter-balance the forces due to the rotation of the earth and the orbit of the sun, a 2-meter tall person should lean toward the east something on the order of an hundredth of a degree.
so the real question is whether you can tell ((without measurement apparatus)) if you are standing perfectly vertical relative to gravity to an accuracy of thousandths of a degree?
just how good is your physical inner ear, really, at determining reality, hmm?
