Why not work as a camp counselor?

Tour guide for multi-week guided vacations. Find a company that needs tour guides that speak your language and see if you can get a job there.

The first thing I thought of is working on a submarine

That is also something I've had some interest in, but besides military (I don't want to be involved with it in any way), I don't think there are that many submarines out there.

Working on the ren fair circuit is exactly what you’re describing. You’re there for a week or a month depending on the ren fair, with the same group of people almost always in warmer weather because ren fairs are no fun when they’re cold. And depending on the job you get, you get to heckle paying customers.

Production/stage hand at events fits up this alley!

Consider jobs involving fieldwork. There are all sorts of jobs that involve a team in a remote / isolated location, and some tend to pay pretty well because most people aren't up for that sort of lifestyle. For example my father was a geologist and could spend months at a time with a team in remote locations, conducting surveys and taking samples.

Old folks home.

Like my grandma has different events everyday and bond with the long term staff.

Treeplanting might be up your alley. Doing the actual job is pretty solitary, you'll see your tree-runner a few times a day, you might have a planting buddy, and the boss might come around once or twice to check your trees.

But outside of the work day, it's very much the camp environment you describe.

You could start as a ranch hand, especially if you know how to ride. You can work on both a regular ranch or on a "resort ranch" that focuses on tourism. You just have to find a ranch that has around that 20ish employees.

But then it would fit all of your points. You are spending your whole day with the same group of people.

Drifting between groups will depend a bit on your exact duties but no matter what you are going to get to know everyone and work with others occasionally.

New things are constantly coming up to do. Your duties also change with the season. And even if there is "nothing" to do you will still hang out with the other farm hands.

You have that authority over you in form of the ranch manager/owner.

Pay isn't great but it might come with free lodging, then it isn't that bad.

I work in construction and when I was younger and single I did a couple years ago a remote work site; two weeks on and one week off rotations. We all stayed in the company provided camp while there. Definitely formed some strong friendships with my coworkers while there and made/saved a ton of money. It was an interesting experience.

I was a field engineer but jobs in the trades are always in high demand pretty much everywhere.

Maybe get into the movie industry. It is a little more long term, they are projects that last several months, but it might be a good environment.

Minimum security prisons aren't all that different than being at summer camp (so I've heard).

edit:

The first thing I thought of is working on a submarine but I was hoping for something a bit less radical. I thought this might be the experience in university dorms but it turns out that in my country dorms are pretty dead because with the exception of cooking, people stay in their rooms.

I've worked on both submarines and at summer camps. I can assure you, they are not similar at all (apart from comradery/ being a part of something).

Strongly encourage you to find work in a conservation corps or similar organization if they exist in your country and you are able to do manual labor. You would be on a crew of 6-15 people usually living out at a field site for 1-2 weeks at a time, cooking and living and working together to improve the natural environment or recreation infrastructure. Hard rewarding work, good peaceful downtime. Great chance to read a lot of books too since you will be away from computers and modernity.

Look for a book called 'Discover What You Are Best At' by Linda Gail.

First half of the book is a series of self administered tests you can knock off in half a day. The second part is a list of jobs that use those skills.

It pointed me at a job I'd never considered, but turned out to be a great fit.

Military?

Event planning. Events. Coordinating. Catering.

You're a burner.

Park ranger?

I found working at a ski-resort and living in staff accommodation to be a bit like this, although there can definitely be a bit more of a "party" attitude, which might be a positive or a negative depending on what you're looking for.

Search Google for Kwajalein Jobs. It's an Atoll in the Marshall Islands that hosts a US military installation, however there is no need to be in the military to work there. I do work there as a contractor for a week every year or two and it sure reminds me of the summer camp I used to work at.

Working for the parks, I have a neighbor who stays home a few days and packs up his truck with a camper and heads off to different national parks for weeks at a time

Public service might be your stick. Firefighter/medic is almost exactly your experience with the new situations every few hours, downtime, having a strong sense of community. Police have a similar feel, if you're in a more rural area. You'll never have the same situation twice, even if things are similar, and you'll almost always have a partner (or more, depending on if the whole truck shows up with the box) to depend on.

I don't know any in particular but I relate to this a lot and commenting to see the other responses that come in

My first thought was working at a startup.

Hotshot firefighting? Assistant river guide someplace like the Colorado? National Park Ranger?

I think you should consider being a seaman, or maybe an oil derrick worker. It seems like the less extreme version of submariner

Opportunities abound abroad, China if you want to go Asia, most places in Europe. They're a bit like English cram courses in China so maybe ESL or STEM.

I lived and worked in a travelers hostel for two years, and it was basically just adult summer camp. Bonus: usually you work for your room so there's technically no rent. There's a lot of partying, and it can be too much at times, but it certainly has that vibe you described.

I mean, you could literally work at a summer camp. Otherwise the only things I can think of that fit your descriptors is potentially field research, or maybe working for a company that follows festivals.

Small team vibes with a lot of downtime and always doing something new? This is probably not what you had in mind, but have you considered research in a university? Graduate school, basically. Academia research is basically exactly what you described, but the downside is, well, you have to be a graduate student. It's not for everyone, but if you're able to weather the suffering that comes from being a grad student, I think you'll find that the vibe is exactly what you described.