You are right. I've heard it described before as if an alien spaceship had landed in 1978, and Eddie appeared from the spaceship playing this sound that had never, in its' totality, been heard before by humans. Many have copied it since, and some did rudimentary tapping before, but nobody did anything like "Eruption" prior to Eddie in any way close to how Eddie Van Halen did it.
I would say "Tomorrow Never Knows" was the start of getting to songs like "I Am The Walrus" for the Beatles.
I remember hearing this one on the old MTV program 120 Minutes and thinking it felt like something more or less completely new: Lush certainly didn’t invent shoegaze or whatever box you want to categorize them in but this song, released in 1990 (a year ahead of My Bloody Valentine’s Loveless album another classic I’m that general realm), really transcends all such labels and is just totally out of left field (and amazing). They had a few killer tracks approaching that level - Scarlet for example - but none quite as unique as this one.
Highly anecdotal, and perhaps more indicative of my own limited frame of reference, but recordings that seemed unique to me when I first encountered them: Are You Experienced, Lady Madonna, Trout Mask Replica, Hot Rats, Glad All Over, Stand Up, Dirty Mind, My War, Ramones, This Year's Model, B-52s...
One more then I will stop - Throwing Muses Call Me also struck me as very much it’s own thing. I sat there with my jaw on the floor after spinning it the first time - after happening across a NM used copy of the LP shortly after it had been released and buying it purely to explore something new, with no preknowledge about what I would hear - just because a) it was a UK import on 4AD and b) like so many releases on that label the packaging was incredible. It quickly became a favorite. Staggeringly brilliant (and they never did anything else to touch this debut album in my opinion). Who else was writing and playing this kind of stuff in 1986???
Metal Machine Music A-4 The first time I played the vinyl and it hit the locked groove...well, there's certainly no precedent for that I said to myself.
IIRC, Joseph Haydn heard Beethoven's 5th during a rehearsal and the compelling energy of the entire first movement (being derived from only a short opening motive of 4 notes), scared him.
Released as a single in 1967, this song, if one may call it such, has no precedent in terms of strangeness especially part II! Googy & Joe's Workshop To Fernanda With Luv Part I
Rosemary Clooney Come on-a My House released in 1951. When I first heard this, I could scarcely believe my ears! A harpsichord doing a rock 'n' roll?!
John Lennon - Mother Very honest, emotional, and raw, especially for an artist of his stature. It wasn't until a few years later that you get a handful of artists that are that honest about their drug, family, money troubles etc.
Fleetwood Mac's "Oh Well", Parts 1 and 2. An immensely entertaining blues song shuffling between Delta acoustics and monstrous electric riffs, paired with what is perhaps the greatest Spaghetti Western composition that never made it to a Lee Van Cleef/Clint Eastwood soundtrack. Peter Green's genius was tragically cut short at the pinnacle of his career. That "The Green Manalishi" was his titanic final song with Mac just shows how sad his mental decline cut off what could have been.