I think I have more characters in their 30s or above than in their 20s or below. At least I do for the humanoids that I use more.
Paladin is 50, but his species has a 160-year lifespan, making him relatively young. His species does reach adulthood at 18 though, so he still has more experience than a 20 year old. He spent much of his life in an isolated village, and has recently come to the discovery that most of the world he thought existed was actually a lie, and is much more modern than he was led to believe. He's still coming to terms with it.
Doc is 34. He woke up one day at around age 31 or 32 with no memory of his former life, and he ended up having to relearn a lot of basic things. He's the protagonist of a horror story so a lot of that wasn't really. pleasant.
The King of Curses is in his 40s. There's not much on his profile but he's the ruler of a kingdom with questionable methods. His wanton use of dark magic causes him to be pretty infamous. He's also known for cursing his subjects to test their loyalty. He used to be a lot kinder, and tried to follow in his father's footsteps, but ending up losing himself in his hunger for power.