When stationed on an overseas US military base in the 70s, I took a Photography class offered by an American University's extension program.
Besides all the technical stuff she also taught a lot about taking pics that didn't make people yawn.
She said something like, "Look for an image that matters, makes us curious, catches our eye, or tells an interesting story".
Posed pics look like ... well ... posed pics - aka boring!
Candid pics of ephemeral moments can really stand out.
One thing we learned was how important it was to develop an eye for anticipating when a great photograph was about to happen.
You have to be ready.
If you pick up your camera AS it happens you're too late.
I embraced this in my world travels in the 70s and 80s.
But today in America people do not want to be photographed candidly.
I remember I attended a PS GTG in Vegas with my telephoto lens and got lots of great shots, but I caught HELL from some there.
I guess they felt it was creepy or pervey, like this openly gay guy was gonna home and jerk off to their pics, or some thing.
Whatever! So much for pursing THAT field of photographic art!
My teacher taught that, with candids, an important aspect was learning how to anticipate compelling facial expressions before they develop.
Also, the direction they are facing, and where their eyes point, preferably at the camera or something that adds to the story being told.
Also, the shot will be stronger if the subject is not facing you, but their eyes are.
You nailed it with this one especially with animal subjects.