The Wikipedia article I cited on the previous page says Kangaroo was in reference to the deep pockets on his jacket.
He was the captain of the Treasure House, of course!
You know, I almost answered that freakin’ question! Then it occurred to me that you really do know…
The original Captain costume included the false mustache to make him look much older.
I remember reading that one time they took his young son backstage to meet Captain Kangaroo, and the kid had no idea that was his father.
Was I the only kid who never understood why he was called Mr Green Jeans?
Everybody knows that jeans only come in one color,—so why give the character such an illogical name?
(yes, it was back in the days when TV was only black and white…)