Op, they are all very much adults. Many adults still live with their parents for one reason or another and many adults, especially those in their 20s, are still figuring themselves out. Abigail talks of college, Sam has a job with Shane at Joja and is pursuing a music career, Sebastian is even more explicitly an adult where he has a career with programing (that no one seems to take seriously), Penny is a teacher to the town kids, Maru is a nurse etc. most of them are adults still trying to figure themselves out and are at different points of life in that.