It means that no human being that lives on earth is worthy enough to put the said ring on his finger, A being from another universe or planet would have to do so.
In Chapter 1, papa has been depicted as a patriarch. Being a patriarch, he has always decided everything in the family. He was 6 foot tall, lean, and hard.
In Chapter 5, papa was a completely changed man. He stepped off the bus at Manzanar looking gaunt and holding a cane.
Because they are physically trained to be able to do anything with either their right or left hand.
The answer is : The tradition is more than 2,000 years old
