Ra's on the case

The Egyptian gods, though normally depicted as humans with animal heads, could really be just about anything they wanted to be. The first Egyptian gods were probably thought to be manifested in animals, and so that was the form in which representations of the earliest gods were depicted. However, they soon took on a number of different forms, including human, and inanimate objects.
Gods like Anubis or Bastet were sometimes depicted as 100% animal, or 100% human, but more commonly they were shown as a mixture somewhere between the two, either a human with animal features or head, or an animal with a human face or body parts.

At best, every image of an ancient Egyptian god is a means of making a god visible by characterizing his nature and distinguishing him from other deities. Of course, attributes of the gods could be shown in many other ways than just the mixed form of a deity.
Other clues to a god's nature might be found in the objects that the god or goddess hold in their hands, in their various headdresses, in their clothing (including mummy bandages), or even in their jewelry