I tried to give a generic overview on the side bar, and it is intentionally vague about the cutoff point because what each person sees as the "perfect" era of minecraft is subjective.
- Pre-classic (May 10 – May 16, 2009)
- Classic (May 16 – November 10, 2009)
- Indev (December 23, 2009 – February 23, 2010)
- Infdev (February 27 – June 30, 2010)
- Alpha (June 30 – December 3, 2010)
- Beta (December 20, 2010 – November 11, 2011)
Anything above this is absolutely relevant to this community. Below is where it gets complicated.
- Official Release, or Java Edition (November 18, 2011 – present)
The official releases is where it gets much more blurry, and I think as long as it is a couple years old, and you have a sense of nostalgia for it, it should count. Perhaps even more complicated is modern version that have been made to behave like alpha/beta/etc versions through mods. I think those should be included as well.
I would still count any posts you make about your 1.14 worlds as relevant to this community. But perhaps a poll would be worth doing.