DtG - I am not sure if I agree with you when you say "Beer only came into being when hops were added".   I've never heard that and I would be curious as to the source.

Beer is a generic term which probably derives from a Latin word for drink. As you noted, at one point all beer was unhopped but the addition of the plant did not change the name. There was a type of beer brewed in ancient Egypt. While they did not add hops, they added other plants for flavor.   Germans were the first to start using it, as you mentioned for a preservative. The UK was rather late coming to the table to use hops.   Regardless, all of it can and was labled "beer". Ale may have been a more common term if that was the only style availble in the region, but it was still beer.   Sort of like calling a tissue "Kleenex".

Do you know why they started adding lime to beer?   Here in the U.S., Mexican beer became popular in the late 50's and 60's when surfers in California would travel down to Mexico to buy cheap beer. At the time, Corona was available very cheap. The legend has it that the lime was added either to give it some taste, or in an attempt to keep flies out of the brew!   Somewhere along the line, the cheap Corona's became a bit of a status symbol, and now the crap is served as a premium!