(his words) mumbo joined back in season 2 when he was just 17, the youngest age for any hermit. A list of hermit’s ages and birthdays (as far as we know): Oldest is tfc in his 60s. 11 votes, 21 comments. So mumbo was talking about how he thinks he was still the youngest.
As it currently stands, i believe the youngest members.
Camila Araujo's Hidden Life: The Shocking Leak
The Camila Araujo Leak: A Mystery Solved?
McKenzie Valdez: The Power Of Information Leaks