“boomer” as a term is here to stay and a moving target
Kind of like how “Millennial” for a while meant ‘teenager’ despite the oldest Millennial being 40.
I mean, it isn’t meaningless, just culturally subjective and lacking a rigerous definition. Berries are a set of specific fruit, which fruit being included being determined by the culture in question base on percieved similarities and historic uses. We use it to quickly bring up the specific group and whatever vague characteristics we percieve them to share.
So, the definition for berries that you seek is simply “the fruit people you’re interested in would point at and identify as a berry”, which is a vague definition and not rigerous at all, but most people would in fact think of the same thing you do if you say “I put berries on top of my cake”. If I ask my wife “hey, on your way home swing by the store and buy some berries, any type will do”, she will not bring a watermelon. She in fact will buy what we both agree are berries, and so the word has useful meaning.
You’ll find most classifications humans have do this too. The real world is really good at refusing to fit into the neat boxes we made to classify it and the things in it, and yet we can still use them fine enough as long as we don’t get lost in semantics and wondering if a hot dog is a sandwich or cereal soup.
Are grapes not considered berries in the anglosphere? In Icelandic they literally are named “Wine berries” and considered as such.
But presumably you don’t just stare at the wall. “Humans need something to do” is mainly bound to not just sitting around twiddling your thumbs. It’s the reason we get bored, the brain is annoyed at not having anything to focus on.
It doesn’t have to be literal work, just something you find engaging, be it going for a run, tending to houseplants, or completing your entire video game backlog.
And of course there is variation between humans. Some people cope well with having little to do, others always need to do something they find productive.