Wasn't only the first of those actually called Aqua? I don't recall exactly when Apple officially retired that designation, but it was well before the current era.

Internally, even the current UI is referred to as Aqua. Or more specifically, aqua and darkAqua, depending on if dark mode is desired.

https://developer.apple.com/documentation/appkit/nsappearanc...

I don't know, but I've seen some people use "Aqua" to refer to the design through 10.4, through 10.9, or through the present day.

I was referring to the earlier iterations, with "shiny" buttons, lots of gradients, etc.

11+ to my eyes has more of a "timeless" potential. It's a bit more utilitarian, less showy and particular.

The early Aqua look and feel was informed by the industrial design of the Macs running it. Consumer Macs were very colorful up until about 2003 and had a lot of the texture effects the Aqua L&F was emulating.