When the mind was stolen by Ravana (the ego) then the soul got restless. Now the soul cannot reach the mind on its own, it has to take the help of the breath - the prana. With the help of the prana, the mind got reunited with the soul, and the ego vanished.
This is the spiritual significance of the story.
Otherwise Hanuman was a monkey, and in those days the monkeys were also very intelligent and very devoted.
Devotees are much more powerful than the master himself. This is a fact. Real devotees are much more powerful than God.