It is also worth noting that The Beatles were superb parodists. Their spoof of The Beach Boys and Chuck Berry on "Back in the USSR" was perfect and the Phil Spector take off at the end of "Happiness is a Warm Gun" is immortal. Only The Beatles would have had the nerve to attempt those psuedo dramatic do wop harmonies with Lennon doing the the absurd talkover, "When I hold you in my arms/And I feel my finger on your trigger/ Then I know nobody can do me no harm..."      
That is absolute mastery of the pop genres - and it's very funny to boot.