It was 44 years ago that...

Miles Davis did it twice with "Kind of Blue" introducing modal jazz, then "In a silent Way" introducing electric Jazz.

Miles basically invented jazz fusion, which open the door for all those groups that came after like Johnny Mac, Mahavishu, Return to Forever, Weather Report, Brand X... JLP.

So Miles really heavily influenced Rock and Jazz.. from Hendrix to Maynard F.

The Doors(st)album has influenced alternative music from the late 70's thru the 80's. It even influenced grunge 20+ years after it's release.

Since someone eventually got around to Pet Sounds, I'll add a single (rather than an LP):

Chuck Berry's 1955 release, "Maybellene", at which time - it could be argued - Rock n Roll is born.

Marty

One could also argue that Little Richard's "Tutti Frutti" released in 1955 impacted rock and roll much more.

Little Richard began recording in 1951, 4 years earlier than Berry.

He is widely recognized as the performer who transitioned rhythm and blues to rock and roll.

Well if you wanna play that game,Rock Around the Clock by Bill Haley and the Comets started the RocknRoll revues that started carrying the sound through out the USA. RocknRoll in the south started breaking down racial barriers in the south.
But to get back to the original posters question
Srgt. Pepper was using new ways to record @ the time,heavily influenced by drug use which was taking off in the summer of love.
Bitches Brew fused Jazz and electric instruments in a raw nervy way making most jazz musicians sit up and take notice.