Hmm. I would say Help! was still 100% the pop they perfected. The transition started with Rubber Soul. I wrote this passage 10 years ago in my self portrait in essay form, published on Medium when I joined 3 years ago https://medium.com/p/7bdac6f1510e, which was my first piece of personal writing:

"The Beatles are proof to me of the existence of “God.” In July of 1964, they perfected pop (A Hard Days Night (their first album without any cover tunes) was released). A few months after releasing Help! in August 1965, they began to take music to a place it had never been before and hasn’t been since. In a year and a half, they released Rubber Soul (December 1965), Revolver (August 1966), Strawberry Fields Forever as the A-side and Penny Lane as the B-side of a single (February 1967) and Sgt. Pepper’s Lonely Hearts Club Band (June 1967). Absorb Rubber Soul, Revolver and Sgt. Pepper’s in that order (I recommend the mono mix of Sgt. Pepper’s over the stereo mix). Hear the nuances and the techniques never before realized and being expanded and perfected over the course of those albums. Universal influence is apparent. The creative advancement, out of nowhere, cannot otherwise be explained."

The Beatles are far and away my favorite band. Like you, they were my first. They found there way to me in '77 or '78, when I was almost 11 or 12, when my mother bought my sister some cassette tapes for Chanukah. Randi was in her Sean Cassidy, Leif Garrett, Tiger Beat pages taped all over her walls phase and one of the cassettes our mother purchased for her was the Blue Album compilation of 1967-1970 hits. Randi hated it. I instantly fell in love with Strawberry Fields Forever, Lucy in the Sky with Diamonds, etc, and a life long love affair with music and The Beatles was off and running.

PS: You really know how to paint pictures with your words, Ben.