Aside: My Master’s degree was focused on the music of Carl Orff, specifically his music for children. I know you’ve heard the selection in this video by Orff.
Full Operas

“L’Orfeo”
Monteverdi
Mozart

“Don Giovanni”

“Aida”
Verdi
Puccini
Wagner

“Das Rheingold”
Bizet
Operas Written in the 21st Century