It is a proper noun as it is the name of a specific person, and is capitalised.
No, John Lennon was a kind and peaceful man.
john is a proper noun
John Lennon
Greek Fisherman Hat.
No, John Lennon is not single.
John did change his name from John Winston Lennon to John Ono Lennon
Musician Sean Lennon is the son of John Lennon and Yoko Ono.
David and Robin are John Lennons brothers.
john lennon
john lennon
John Lennon does not sleep he is dead.
John Lennon is very famous.