why is the creatures appearence relevent? what science is shelly disregarding

There is a fantastic article at the site listed below that deals with nothing but the creature's appearance and lack of acceptance. You might find it quite helpful.

In Chapter 11, the monster searches for food, but when he finds a hut and enters it, his appearance causes an old man inside to shriek and run away in fear. He then proceeds to a village, where the sight of him causes even more people to run away. Because of these experiences, he resolves to stay away from humans.

In Chapter 12, he spends an inordinate amount of time admiring his neighbors and the way they look. After catching sight of his reflection in a pool of water, he retreats but continues to watch them. He even becomes somewhat attached to just being near them.

She has purposely disregarded psychology; it's a lesson for the reader.