The Beatles could have done an amazing cover of LaVern Baker's "Tweedle Dee" on the BBC, circa 1962/63, with McCartney taking the lead vocal. The song has those quasi-Calypso rhythms they used throughout their career. Elvis covered the song on the Louisiana Hayride, but he took out the Calypso swing, made it a more straight-up rhythm and blues number. Heres' the Baker version:
What do I mean by the Beatles' quasi-Calypso rhythms? That starts with Ray Charles' "What I'd Say," which the Beatles would jam on for upwards of twenty minutes on the Reeperbahn in Hamburg. The Calypso rhythms start at :16 here in Charles' version of the song.
Do you hear the swirl of those drums? Note the role the cymbals play in that circular, swinging, swirling effect. The Beatles heard that and thought, "Right!" (NB: Consider how modern the Charles two-parter is. It's one of those records that sounds like it has lasted forever and has also arrived in the here and now from a time that has yet to come.)
Now, you need a drummer who can play this way. Ringo Starr is a huge reason the Beatles were the band that they were, and could become the band that they did. Adventurous songwriters could do a lot knowing that they had Starr in the drummer's chair. You need his range of styles to do "She Loves You," "A Day in the Life," "Come Together."
Let's look at the band's "I Feel Fine" now. How do you think of the song? As a work of late Beatlemania, most likely. But it has a real Latin inflection, because it's built even more around that quasi-Calypso swirl as it is the souped-up Merseyside guitar riff. The "swirl" starts at :14. Here that? Here Starr working the cymbals? Do you feel the musical motion in which we're going? It's almost like being in a dryer, isn't it?
Here's another example with "I Want You (She's So Heavy)" from Abbey Road, the band's final album, five years later. Here the swirl breaks the tension and makes the song less angular, cuing a dance a section that is at once a legitimate dance section, but a borderline satirical dance section as well. It's like in that old cartoon when the skeletons dance; they're meant to be dancing, not you, the living person. This is a little like that. Listen to the shift into that swirl at 2:24. This is a chunkier, slower swirl--the dryer is on a lower cycle, as it were. But it's the same idea, and it's that same Calypso-tinged rhythm and blues.
See? That's straight from Ray Charles, but processed by the Beatles' sensibility. It's something one will find discussed later in my book Same Band You've Never Known: An Alternative Musical History of the Beatles, and also a book on the genre of British rhythm and blues, and how American Black musicians helped teach those English artists to become what they ultimately did.