Recorded rap has been in existence now for 40 years.
Singing has existed since its inception.
Here's a thread.

Positive Force "We Got The Funk" (1979)

Disco Four "We're At The Party" (1982)

Sweet G "Games People Play" (1983)

Crash Crew "On The Radio" (1983)

Break Machine "Street Dance" (1983)

Force MDs Meet The Fat Boys. (1985)

Whodini. Larry Smith. "One Love" (1986)

MC Shan. T.J. Swan. Marley Marl. "Left Me Lonely" (1987)

What exactly is Pete Rock doing here?
On Illmatic?

AZ. "Gimmie Yours" (1995)
That's Nas singing the chorus.