Just how influenced were the Beatles by other people?
When they finally "became" the Beatles as we know them, dressed in suit and ties and singing in unison, they took that directly from the Everly Brothers as well as possibly Buddy Holly and the Crickets.
The Beatles had a huge influence on many Garage rock bands that would spring up, but I am certain the Beatles were influenced by many of them as well. These bands took what the Beatles did (and Stones) and started coming with their own sounds, and were a lot more edgy, especially in America's west coast. Bands like the Count Five (Psychotic Reaction), The Seeds, The 13th Floor Elevators, Electric Prunes, Strawberry Alarm Clock, etc, there are too many to name. These bands could be viewed as a type of proto-punk.
The album Sgt. Pepper was the result of Beach Boys' "Pet Sounds".
The Beatles were not the first psychedelic band, they simply followed the trend.