RMartinez:
That is your opinion and can never be proven. The Beatles were a collective phenomenon. Your thesis says even Paul would have been famous as a solo artist, or John would have been. But that can never be proven. If the Beatles never made it, Paul may have become a teacher, and played music for fun. John may have become an artist or factory worker. The Beatles didn't pick up a hack drummer to start their rise to fame, they got the best rock drummer in England, Ringo, because they KNEW they sounded amazing with him on drums, never mind his charismatic personality. George Harrison had a chemistry with John and Paul that took years to cultivate. People who say a band could have made by just putting another drummer in there or another guitarist don't really know much about how things work. If you are right, then why didn't they just keep Pete Best on drums? Because if they had, we would NEVER have heard of a band called The Beatles.
Well, that is also an opinion, and it can never be proven either. Any of this is speculation, but that doesn't make it baseless speculation either. John and Paul wrote the music and sang most of the songs, so I don't see how they wouldn't have made it, as the Beatles, without Ringo (and even George). That isn't to say they were not better with them. But think of the songs that started Beatlesmania: She Loves You, I want to hold your hand. Those songs would still have existed... When I said John and Paul would have made it solo, or with a band not including any of the others, that is of course starting from the assumption that they would have still pursued a career in music. They both were/are too great songwriters and singers, with great charisma as well, for them not to have made it had they followed that path. I do think there's a good chance they wouldn't have pursued a career in music without each other, but that's another discussion. I mean, John's band wasn't all that serious before Paul came in, and Paul even sort of quit the Beatles after their first Germany trip. He probably would have falled under his dad's pressure to get a real job without John's influence. Paul would probably have been a teacher and John had could have well become some sort of visual artist. Now, Paul did know George on his own, and his own brother formed a band later on, so maybe in this alternative universe George would have found himself in a band with two McCartneys lol. Anyway, I quote Hendrix here 'cause I think he explains it very well:
Hendrix Ibsen:
I think both John and Paul could have made it as songwriters/solo artists already early on if The Beatles hadn't happened. It took a while longer for the George to come up with the genius songs. Or they could have written all these great songs for others to sing, Lennon/McCartney had many giveway hits and it wasn't even their best ones. But The Beatles as a band... The combination of those four is so unique... The record companies have tried put together "beatles bands" since 1963/64, and they can't! John. Paul, George, Ringo... The greatest ever. It's just the way it is. 
I'd consider that to be Paul's first song with this kind of theme. A couple people mentioned I'll Follo the Sun, but I don't see how it'd be a comforting song? lyric-wise of course. Such beautiful harmonies with John in that song. It's one of my favourites... and to think he wrote it being so young. There's a place could be, but it's not really Paul's.
Not famous at all then, so no reason not to go up the tower.