OK, if noone else will give the history lessons . . .
RC churches did not have pews until the Reformation. Pews first appeared with the protestant emphasis on the sermon, and were put in for that long part of protestant worship. They spread to the RC from there (and in the US, spread to the EC as an americanism rather than a latinisation).
Kneeling serves two roles in the west: it is the position of penitence, and also of respect.
As a penitential posture, it is ancient. As a matter of respectt, though, it (and genuflection) trace to its position as respect to earthly kings. Respect given to earthly kings would certainly also be due to the King of Kings.
So peniticial kneeling is ancient, while kneeling for respect is far more recent.
In the East, kneeling is only penitential, while
standing is the position of respect (and we don’t only kneell, we prostrate. In fact, there are ancient canons from the councils anathemizing those who kneel on Sunday, but this refers to peniticial, not respectful, kneeling.)
sidenotes:
- the Novus Ordo does not, as suggested above, require that the priest face the people. In fact, it assumes that the priest is facing east, as do the congregation, and the rubrics instruct him to turn towards the people at certain points.
- My family history is loaded with bad knees. My grandmother blew out both snooping about EMTs across the street, my brother injured his at soccer, my sister in gymnastics, and I was justt short of surgery from standingup at my desk . . . I had been bracing myself on the pew for every genuflection and to kneel for years before turning east. My knees feel much better now

hawk