It’s based on perspective. If you’re going north on a globe, and you spin the earth toward yourself, you will continue to go north. Similarly, if you’re a third party watching someone going east continually (without the globe spinning); then by the time the person going eastward ends up “behind” the globe from the third party perspective, then they will be going west for a short period of time. 3D space is weird.
The first bit of your statement is incorrect because globes have a set point in which there is a north-most and a south-most position. Going north is defined as approaching the north-most position and going south is defined as approaching the south-most position. No matter how you spin a planet in relation to yourself those positions are absolute as they rely on the magnetic field to get their placement.
Uhh...no...if the globe is spinning toward you at a constant rate, and you are traveling north at that same rate, it would appear that you are indefinitely heading north. I should reform to say, it’s about circumstance and perspective.
Even if you are looking at it from a different angle it doesn't change the absolute positions of northmost and southmost. No matter where you are looking from you will eventually step on the northmost spot and no longer be walking closer to the northmost point. No matter your angle on the person that is walking they will be visually walking away from the nothmost point after walking a far enough distance
technically north-south are cycled directions just with each half of it counted individually which allows for a endcap where the two halves meet. This could also be done with east and west however it would have an infinite number of endcaps because of the aforementioned parallel status
east-west are parallel cycled directions.
north-south are radial directions to endpoints.