The original 3 started out as teenagers and honed their skills with many hours per day on the Hamburg stages for months at a time. All learned and shared what they learned as their fame grew.
(Pictured above: Paul McCartney, Ivan Vaughan, and George Harrison. Ivan introduced Paul to John.
(with Pete Best.)
One story from Donovan has John learning a new technique from Donovan in India. Paul observes for a moment and goes off to not only learn it from the brief look but to change it into a different way to play it. John used the style he learned in Dear Prudence with great skill.
George tried to learn sitar basics and later switched from guitar to slide guitar. He was chosen to be the lead guitarist and did the job well throughout the Beatles’ years. But to be realistic, his true growth was from composing songs with the Beatles. He went from zero songs in 1962 to composing songs until his last four songs rivaled those of the other two composers. Something is one of the best-selling Beatles songs downloaded in the past decade.
Ringo remains honored as a Beatle and a great drummer who has influenced many drummers who have followed him. But he basically learned his craft before the Beatles, and his playing got even better as he supplied whatever beats the Beatles needed for their inventive songs.
But Paul wins in this context.
Paul was playing guitar when they were in Hamburg, but took up bass when Stu left. From an amateur at bass, Paul rose to inspire future generations with his bass playing. He also improved his piano and keyboard playing during his Beatles years.
Paul continued to improve on drums, piano, and dozens of other instruments during the 60s.
By the mid-Sixties through the Seventies, Paul rose to the top of his peers in music with his bass playing as well as a composer, as part of the Beatles and later the band Wings and a superb solo career!
He also learned from George Martin to become a top producer of songs and albums in the studio!