And to not put your phone on the camera lens, I would put it in a case that is as thick as the thickest glass part, which looks not that slim.
(Their dimensional volume is close, and their weight almost the same.)
IE the idealized hourglass 36-24-36 is considered thinner than a woman at 34-30-34.
Also, the numbers are top to bottom so IMO the phone would be 48-24-24, a rather absurd proportion for a person and possibly why phones seem so ugly these days.
I think for people thin is mostly in reference to volume for a given height. But there’s a bunch of related factors involved like weight and clothing sizes which keeps it relatively ambiguous.