I didn't make up the concept of the Gestalt of a world myself, I read it in a book I no longer own, so my own memory of what it exactly means may be hazy.

When I say "visual", what I mean is really "easily imaginable". A Gestalt works a bit like an advertisement: imagine someone has never before heard of your world. If you had a movie poster to show it off, or a tagline, or a one-sentence description, what is the unique and central feature of your world that would make a person say "tell me more"?

I cannot speak to those example you just gave, since I don't know of most of them (the obvious exception being Captain America). I would hesitate on calling any of them Gestalts, since, by your descriptions, they do not seem unique enough to capture the interest, without already knowing something about the IP. But if you can describe or show them such that you explain a unique (and important) aspect of them that is intriguing, then they might be Gestalts. Like I said before, to simply say "The One Ring" would have been a bad example, since you'd have to already know what we're talking about to not assume LotR is a love story. To say "There is one ring which grants unlimited power to those who are powerful enough to wield it" can get much closer to a Gestalt, since we are now not only describing an item central to the world, but also describing what makes it unique from other rings in other worlds.

Also, I capitalize Gestalt because I get weird about vocab words. I try not to, but I capitalize too much! :p