Here’s a blast from the seventies no one needs: “Alone Again … Naturally.” First one to pop into my head after “Afternoon Delight”…
I Will Survive - Gloria Gaynor
Hooked On A Feeling - Blue Swede
Knock Three Times - Tony Orlando & Dawn
I Am Woman - Helen Reddy
Uncle Albert/Admiral Halsey - Paul & Linda McCartney
Everything Is Beautiful - Ray Stevens
Brand New Key - Melanie
Don’t Stop 'Til You Get Enough - Michael Jackson
Shilo - Neil Diamond
That’s always been my interpretation, too. But others have suggested that the narrator’s relationship has just ended, and the song is encouraging getting on with the next rebound relationship. [Which is typically a terrible idea, but a lot more forgiveable.]
ETA: Woops - it looks like I have inadvertently revived a 10-year-old thread. Well past the six month statute of limitations. )-: Sorry, it was an accident! I was referred here by another recently revived 10-year-old thread, and didn’t realize this one was still asleep.
“Oh, Babe! (What Would You Say?)” — Hurricane Smith
“Dance with Me” — Orleans
“Back Home Again” — John Denver
“Top of the World” — The Carpenters
“Only Yesterday” — The Carpenters
“Rhinestone Cowboy” — Glen Campbell
“The Last Farewell” — Roger Whittaker
“Silly Love Songs” — Paul McCartney and Wings
“Calypso” — John Denver
“I’m Sorry” — John Denver
“Fernando” — ABBA
“Dancing Queen” — ABBA
“Year of the Cat” — Al Stewart
“Suspicious Minds” — Elvis Presley
“Cold Kentucky Rain” — Elvis Presley
“Nobody Does It Better” — Carly Simon
No zombie songs in the 1970s?
Seriously though; it seems like the 1970s were insanely all over the map in terms of musical styles and what was defining for each style for the 1970s.
I mean, you have stuff like the Bee Gees, which is definitely iconic 70s music, but you also have the Village People, the Allman Brothers Band, Molly Hatchet, Lynyrd Skynyrd, Elvis, John Denver, “Outlaw” country like Willie Nelson & co, Barry White, Stevie Wonder, Led Zeppelin, Elton John, Billy Joel, The Eagles, and so on. All of which were very 1970s in their day, very popular, and still iconic for the most part.
It seems to me like the 1970s was an era of unprecedented musical fermentation, and trying to pick ONE band/song as “Seventies-est” is not going to get you much.
They used that one on South Park one time. John Stamos’s brother sang it.
“Listen to What the Man Said” by McCartney and Wings.
Or “My Life” by Billy Joel.
Or “You’ve Got a Friend,” James Taylor version.
My pick would be Undercover Angel. Alll Righttt!
A lot of good replies, but the first thing to pop into my head was “Dancing Queen”.
“Brandy” — Looking Glass.
“Heart of Glass” — Blondie
“Live and Let Die” — Paul McCartney and Wings
“Waterloo” — ABBA
“Crocodile Rock” — Elton John
“Your Song” — Elton John
“Goodbye, Yellow Brick Road” — Elton John
“Rocket Man” — Elton John (Though I prefer Shatner’s version.)
“Save Your Kisses for Me” — Brotherhood of Man
“Money, Money, Money” — ABBA
“Knowing Me, Knowing You” — ABBA
“Don’t Give Up on Us, Baby” — David Soul (Yeccch!)
Life During Wartime was from Aug 1979; hardly representative of the decade which was in the throws of ending. Great song though.
Ahem!
Thanks for the spelling catch!
You’re velcome! 
In broad strokes, I look back at '70’s music in three genres.
Pre-1975, Rock. Epitomized by Stairway to Heaven and Smoke on the Water. Heavily influenced by the white Blues of the '60’s.
Mid '70’s-late '70’s/early '80’s. Disco. The Saturday Night Fever and The Hustle. Influenced by EuroPop
Late 70’s - The Disco Rebellion. Heart of Glass a direct jab. Jazz influenced songs like Baker Street and FM. Soft rock and folk/country influenced songs like Operator and Rocky Mountain High
Nope. It’s Minnie Riperton, Lovin’ You.
You shoulda heard my dad hit those high notes as he zoomed around town in his Karmann Ghia convertable with the top down.
S A T U R D A Y
First, the most seventies song should be one that was a hit in its time but has never been heard since and no one has covered. Just a shock when you are listening to 70’s compilation that you remember that song you haven’t heard in 40 years.
Second, you have a decision to make.
Well, given those criteria, I’d have to nominate “Shannon” by Henry Gross. https://youtu.be/R5Wpn3dFrEs