My vote (like many others) would be for Blitzkreig Bop.
I’d also say Last Caress by The Misfits. (NSFW lyrics)
The Misfits were really hardcore punk to me. Check out the crowd in this performance. Black Flag is really hardcore too, although I never liked their sound as much.
By the way, don’t confuse the new Misfits (without Glenn Danzig) with the original Misfits. The original Misfits ended in 1983 or so.
Fresh Fruit for Rotting Vegetables - The Dead Kennedys
Kill the Poor
Chemical Warfare
California Uber Alles
Holiday in Cambodia
Four of the best punk tracks of all time on one album.
Search and Destroy - By Iggy Pop
Waiting Room - By Fugazi
Anarchy in the UK - by some band I can’t ever remember the name (j/k)
Lost in the Supermarket - by The Clash (I LOVE that damn song).
Yeah, you’re right. Even though they say fetuses can hear in the womb, my parents claim they didn’t know that punk existed in the 70s, so I definitely didn’t hear them in '76 