It makes sense that left and right is more abstract to our brains than up and down. As humans we’re symmetrical from left to right: my right hand is a mirror image of my left. We’re asymmetrical up and down: my feet are different from my head. We also have gravity which our whole lives points down. There’s no equivalent to that in left vs right.
Whether something is up or down is more meaningful in terms of our average interaction with that object than whether it is left or right. Conceptually the latter is inherently relative to the observer, and in many circumstances the observer could just turn around to change the state of whether it’s left or right, so it doesn’t matter which way it is. Whereas they can’t do as much about many things that are “up” or “down” like the sun, a tree canopy, the earth’s mantle. Those things are more constant generally so it’s easier to grasp them
Also, in a mirror right and left are always swapped, but never up and down. Not even if you tilt your head or cover one eye
I thought I was the only one.
