This is a question as old as time itself as it appears to predate even the ancient civilization in itself. Why did the ancient Egyptians use animals to showcase the ancient deities that they praised?
Take for example the ancient God Anubis, the god of the dead. He was being represented by a humanoid being that had the face of a jackal and the body of a man. This, many believe is thanks to the fact that whenever jackals appeared, they always showcased the fact that death had occurred nearby.
For example, they were akin to modern-day vultures, as they would be attracted to the scent of blood, and wherever they were you’d be sure to find the remains of someone or something. On the other hand, many believe that Anubis was never evil, to begin with and that his whole facial features would change depending on who he’d deal with.
If you were an evil being, for example, he’d show himself as a jackal with a human body but if you were a kind and honest person, he’d show himself like a dog with a human’s body.
Horus on the other hand was the son of Osiris and Isis and amongst all of the ancient Gods, he is believed to have been the wisest and fairest. He is represented by a falcon-headed humanoid being and is often known as the God of wisdom according to Egyptian lore.
Falcons were deemed the carriers of information and they were often used by the Pharaoh himself to order his legions. This is why he was known as the God of Wisdom in the first place. So, as you can see, we can do the same with every other anthropomorphic being throughout the Egyptian mythos, as their animalistic features were inspired heavily by the representations that portrayed.