I thought about the age of Ministry employees.
I think that there was once a rumour about Harry becoming Minister, and Rowling said he was too young at age seventeen. Which would mean that all Ministers have been older.
Aurors: Requires a completed Hogwarts Education and a three-yeqar training, which would mean that normally Aurors are at least aged 20.
Heads of Auror office: I think Harry was said to have been the youngest Head of Office in 2007. In 2007, Harry was 27 years old. Should we add that the other Heads of Office were older?
normal employees: Has it been stated in canon that they were required to complete school. If this is the case, they are all at least 17 ywars old.