I listened to a fascinating conversation on the TED Radio Hour between writer Tracy Chevalier (Girl with a Pearl Earring) and Guy Raz. Chevalier talked about growing a whole novel out of a single painting. If you haven't listened yet, I highly recommend it. She said one thing in particular that really stood out to me as a short story writer:
"We have dramatic lives, though they might not seem dramatic to the outside, but to us it's those little daily incidents of life that are dramatic, and if you put a frame around it—an actual painting frame, or if you put a frame that is a novel around small incidents—they suddenly become bigger because you focus. And anybody can focus on things that don't seem to mean much, and suddenly they become much bigger and much more important than you ever imagined."
I would argue that the short story also frames these small, uncelebrated moments, zooming in and examining the minutiae of a life, pixel by pixel.