If the Garden of Eden is a right reality that is well with God. If it is the Spirit world , it is a realm of importance. A snake is simply a being that is able to enter and leave this realm at will. A snake is able to exist both inside and outside this Garden.
So by our logic, The Snake is both Cherubim and Earthly for it goes inside and outside the Garden. A snake is simply the beingness of free-willed Cherubim. That is , We have identified a type of beingness that Angelic being try to obtain, for A snake’s will is free, but its true home is within the Garden.