"All together now" is a fairy easy kind of song with not very demanding lyrics. I cannot recall that it ever was a hit. During the greater part of the sixties, I was in the Far East a great deal and missed quite a lot of the Beatles antics. I really got to know the song when browsing through Beatles Songs for the Recorder
With the "Bompa, bom, Chop the tree ...."
bits, it is ideal for children to clap to or stamp their feet. I do not know whether there is any deeper significance as with "Lucy in the sky" for example. Perhaps some Beatle Type Surfer could clue me in!