Iron Man ended with the Black Sabbath song of the same name, and now Captain Marvel ended with "Celebrity Skin" over the credits. I can't recall off-hand if any other of the films have used already-known songs the start of the credit roll, as opposed to new music as part of the score.
They sure have!
Iron Man 2, unlike most other MCU movies, doesn't have a fancy animated credit sequence, but AC/DC’s “Highway to Hell” plays over its last scene and continues into the credits.
Guardians of the Galaxy also doesn't have a fancy animated credit sequence*, but “I Want You Back” by the Jackson 5 plays over the “The Guardians of the Galaxy will return” screen and the pre-credits scene, where newborn Groot appears to dance to it.
Guardians of the Galaxy Vol. 2 does the same with “Surrender“ by Cheap Trick (although it continues over the credits), and later we hear both “Flash Light” by Parliament, and “Guardians Inferno” (featuring cast member David Hasselhoff).
The animated credits for Spider-Man: Homecoming feature “Blitzkrieg Bop” by The Ramones.
Black Panther's animated credits have “All the Stars” by Kendrick Lamar and SZA. It's from the soundtrack, but it was released as a single about six weeks before the movie came out.
Spider-Man: Far From Home has “Vacation” by The Go-Go's over its animated credits. (For the record, we also hear “A Message to You, Rudy” by The Specials playing in the background of its post-credits scene).
Eternals ends with “Feels Like the First Time” by Foreigner (feels like the last time more like)
Spider-Man: No Way Home has “The Magic Number” by De La Soul over its animated credits
Thor: Love and Thunder has "Sweet Child of Mine" by Guns N' Roses over its animated credits, as well as "Rainbow in the Dark" by Dio over the first part of its black-and-white credits.
* Guardians does have “I'm Not in Love” by 10cc over its opening flashback, and has a title card and credits early on in the movie, backed by “Come and Get Your Love” by Redbone. Guardians 2 follows a similar pattern with “Brandy (You're a Fine Girl)” by Looking Glass and “Mr Blue Sky“ by ELO respectively. In a sort-of similar fashion, Spider-Man: Far From Home opens with “I Will Always Love You“ by Whitney Houston.