i mean, the beatles weren’t really the first, though, that was just how the label system worked, like, look at american rock or R&B bands from the 50s, and that’s really common
My pre-Beatles knowledge is weaker but I tend to think of that equivalent as more of the crooner era (e.g. Sinatra).
Did they have the magazines about them and the slotting the members into particular roles side of thing before Beatlemania?
The shape of rock bands is set in the 1950s (and Andrew Hickey is the go-to on any of this). How this works out in terms of individual artists and the maw of commerce is complicated.