Team Fortress 2 might be exactly what you're looking for. It's free and the community is pretty laid back. Read about why it's still doing well at https://www.southwestjournal.com/gaming/why-team-fortress-2-is-thriving/ and it made me want to jump back in. The game doesn't take itself seriously and matches are chaotic fun instead of stressful. Plus there's tons of different classes so you can switch things up whenever you want. Been playing it casually for the past month and it's a nice break from competitive games. Worth trying since it won't cost you anything