Kind of a weird question I know, but let me explain. I'm not talking about your themes or messages, but the general feeling someone looking into your world or imagining themselves in it might get about the situation, when the world is not in conflict. Basically, you know how when you watch a franchise like Star Trek, it has certain recurrent moods and feelings, like the tranquility of flying through space, the bittersweet isolation of being on a ship in deep space, where you are close to your crewmates but far from everything else you know, and the general professional but still sufficiently jovial atmosphere that they seem to go for? Or with Pokemon when it's very adventure driven and based around meeting everyone you come across and making friends both with other humans and also with these magical creatures! I'm sure you can think of descriptions like these for your favourite franchises. We've all imagined ourselves in these worlds or imagined ourselves as characters in these worlds right? What were some of the vibes or feelings you imagined when you imagined your world? Or I guess another way of putting it is what would a slice of life exploration of your world be like?
For my post-post-apocalyptic world, the main feeling I'm going for is hope. The idea being that some time far in the past a great calamity happened, but humanity has rebuilt, and despite all the great setbacks nothing can stop people from reaching ever higher (indomitable human spirit, etc, etc).
Another feeling I'm going for is the sadness of knowing that some ancient civilizations are lost, and we have no records of them and how they lived, and these things that were so important to people of the past are just gone forever. In my world the knowledge of the old world from before the apocalypse is fading, their buildings are eroding away, stories of them are slowly warped until they're unrecognisable, and the artifacts left behind are lost one by one.
I guess these combined also creates a theme of moving on, though I don't think that counts as a feeling.