“‘Let It Be’ was the last album. Wasn’t ‘Abbey Road’ just before that?”
You are correct that “Let it Be” was the last album released. “Abbey Road” was the last recorded. Some say that Let it Be was such a mess that the band wanted to finish their work on a stronger note. I’m not sure I believe that, but Let it Be has historical significance in the sense that it chronicled the band breaking up. I don’t think that was their intent when they started it, but that’s the way it turned out.
The magic had run its course.
The last of the "magic" was Revolver and Rubber Soul.