Very clearly sung, good diction, and lyrics, in good English, that make sense:

"The Ugly Duckling," Danny Kaye:

https://www.youtube.com/watch?v=-Ok6Y77DeNA

Solo songs from the 1960s "folk revival" in the United States might do. They are clear, the lyrics often make at sense (tell a story or make a political point), and the singing is often fairly naturally enunciated (rather than being distorted in the interests of musical beauty).

"Sailing Down my Golden River," Pete Seeger

https://www.youtube.com/watch?v=O9SNWCFH22w

"Both Sides, Now" Joni Mitchell

https://www.youtube.com/watch?v=Pbn6a0AFfnM

Not a folk song, but I like it a lot: "The Rainbow Connection," Jim Henson ("Kermit, the Frog")

https://www.youtube.com/watch?v=jSFLZ-MzIhM

Love yourself - Justin Bieber

Shape of you - Ed Sheeran

7 years - Lukas Graham

They are "slow" songs nice for learning

By the way, take care as I know "love yourself" has some grammar errors (e.g. my mamma don't like you).