Recently it struck me that although the Bible doesn’t refer to animals speaking to humans in the Garden, Eve’s reaction seems to me very strange. If other animals talked, then Satan’s conversation wouldn’t have necessarily seemed out of place. But, if none of the animals talked it would have been quite a shock. If an animal began speaking right now to you and you hadn’t seen that ability in other animals wouldn’t you at least think it was strange and perhaps talk to God about it before you responded to the animal?
I agree. This is not something we would consider to be normal. But Eve’s reaction, or lack thereof, indicates things might have been different then. Also Genesis 3:1 says the serpent was very crafty or sly. And the Hebrew word translated serpent comes from a root that means enchanter, so he might have cast a spell of some kind over her.
Balaam didn’t seem very surprised when his donkey started speaking either (Numbers 22:21-35). Maybe the Holy Spirit just didn’t see fit to have Moses include their reactions when he wrote about these events.