While having quick reflexes is always a benefit, positioning and teamwork is more important in Squad.
Finding a server with consistently decent squad leaders is definitely important to get the most out of the game. If the squad lead isn't talking for more then a minute or two, leave and join another.
I'm 40+ and play Fortnite with my son, and while I worry his gaming exposure is very heavily weighted to one game with minimal story, we have a great time working as a team and talking about strategies to maximise our chances. He's 9yo and a very strong player. I don't find reflexes to be that much of a problem, but I'm not sure how old you mean by "older"!
You might like The Battle of Polytopia. Not the same but has similar vibes.
https://www.beyondallreason.info/
Watch this space, it's already decent and also OSS.
PS: One hill I will die on is games using Discord as forum/wiki like this one does. Try searching google for information about unit or something, nothing. I guess I will have to make unofficial wiki/forum one day.
If you like your FPS games with a side of inventory management and googling around for wiki hints, have a look at Escape from Tarkov. I'd suggest watching a bunch of Pestily's content (his The Raid series on youtube) to figure out if the game is for you. IMO it rewards experience over reflexes - but may be a different kind of 'experience' from what you are interested in. Lots to learn about map layouts, ammo types, etc.
Also have a look at the new Arma game (called Arma Reforger), seems like it could be (or become, with updates) interesting.
FWIW I've recently gotten an Oculus Quest 2 and I've been playing a lot of Pavlov Shack. I was afraid of the quick-reflexes, playing-all-the-time, fearsome 14 years old (and judging by their voices, there's a lot of them), but I've been doing pretty well - usually ending up with a 2:1 or 3:1 K/D ratio, top of the team table, and playing maybe an hour every other day. I'm very surprised by this, and I can't really explain it - I'm not a gamer and the last time I played an FPS seriously was before 2010. TLDR: Go get 'em!
2 - Updated subspace - it was the level of competition and community that made that game amazing in the 90s.
3 - Civilization like civ 1 but updated with newer graphics/tech tree also the ability to be much more complex but only if you want to. Best part of the game imho was the exploration, simple but enjoyable tech tree and expansion. The new civ games are fun but take so much time to master and engage in.
4 - FPS that can be played in large scale format but doesn't reward 14 year old reflexes and levels the playing field for experience of older people.
Video games that are easily accessible, enjoyable and don't try and keep you on platform by wasting your time on meaningless accomplishments :D