What I found interesting about Jerry Lewis was that when not in goofball mode he was totally unfunny and stern - I could have easily imagined him as a Nixon advisor or a NASA or CIA hardass in a non-comedy movie, he had that air about him. I remember a German TV show in the seventies where they played his famous typewriter sketch
before the inteview and audio and film were ever so slightly (really just a little bit) off sync and he noticed immediately and it visibly bugged him throughout the interview, he was uncomfortable. He was a perfectionist and very hard worker. I certainly do not agree that he was talentless even if devoid of Dean Martin's natural charm on or off camera.
Jim Carrey reminds me of Jerry Lewis. They both have that slightly dark psyche looming underneath the screwball antics. And Ronald Atkinson's acting as Mr Bean - another troubled soul pulling faces - owes a lot to Jerry Lewis too.