Yeah, you are correct on the origins on the word “Pleb”. However, in ancient Rome, Plebians actually rose to the level of what we would call “upper middle class”. They owned homes etc and were respected.
Today, “pleb” is a very negative term. Almost like the word “servant”
Regarding “posh”, yes that is where the word came from, but now the word is abused beyond belief in the UK. It is used for things that are best described as “tacky” and certainly not “Posh” in its original incarnation
Plebians could indeed rise from humble origins, but had no representation in the Roman Senate until the rank of tribune, elected by the plebians, was created; a tribune could block the will of the Senate by announcing “Veto!” (I forbid it!).
Don’t know why, but I have begun viewing episodes of “Keeping up Appearances” on youtube. The outtakes are absolutely hilarious. But there really isn’t anyone like Hyacinth at large in British society, is there? Poor terrified Elizabeth trembling at the approach of that Bucket Woman can be difficult to watch.
;^)