Rowing. It's a great sport for older people as you get a full-body workout and you don't have the pounding or twisting and turning of other sports. Plus since there are no real stars in a boat because everyone is pulling, it's a great team sport. Yes, there are folks who rowed seriously in college and have that high level competitive experience but most of us took learn to row classes when we were older and we feel just as much a part of the club as the former collegiate athletes. I also enjoy getting to know people from a range of ages from their 20s to their 70s.
If you want to know more, Capital Rowing has learn to row classes. See
https://www.capitalrowing.org/crcwp/join/learn-to-row/ And if that location is not convenient, there are lots of clubs in the DMV and around the country. Check out US Rowing's club page:
https://usrowing.org/sports/2019/10/24/find-a-club.aspx