Focal length equivalent assumes a 35mm sensor or film format. 50mm on 35mm is basically the human range of view (although human eyes are interesting in that our resolution is so much sharper in the middle of the sensor than on the edges, and there's significant variation between individuals.
But the important part is that it isn't actually focal length that makes the effect. It's distance from the camera. If you do a dolly zoom with a fixed focal length lens, where you still push or pull the camera towards or away from a subject, you can still see this effect on the nose and the ears.
A flat, two dimensional representation of a three dimensional object will always have distortion. The effect we see here is about distortion that changes with camera distance, and the change itself is what makes things feel strange.
Yes, but I bring it up for the specific example of using our own eyes to achieve this effect, rather than relying on a camera. We don't have a choice to change the focal length of our own eyes, or even crop the image, but the effect is still there.