Don't over-interpret: It is just way easier the way we are built, kids learn climbing stairs (and other things) way before they can safely walk stairs downward

Don't over-interpret: It is just way easier the way we are built, kids learn climbing stairs (and other things) way before they can safely walk stairs downwards. The smarter ones go backwards. Standing on a step and stepping down is just ... complicated ... and requires considerably more body control. The risk of toppling forwards and falling down the stairs (or the couch) is considerably higher than "stumbling the stairs upwards".