Mesopotamia has always been considered as the original heaven with its tree of life and its marvellous animals, and this, in a world where the human had yet to appear. Therefore are we renouncing at the representation of the first couple and the snake lying at the foot of tree of temptation? Indeed, before being the Garden of Eden in the bible, it was already present at every era since the 4th millennium in Mesopotamia.
Nevertheless the tree of life, plentiful of fruits, blessing of god, was also present as an artificial form of gold and bronze, mostly located in the numerous Palace courts of Assyrian kings.
It was the symbol of immortality and was often represented between two prayers or priests leading contemplation to adoration. We will find it again on other paintings of Philhelm.
The sea with its fish is there to remind us that for Mesopotamians the human being came from the sea. The lion, king of animals is the only one watching us, he was the incarnation of cosmic forces.
Only kings had the right to hunt them, even exterminate them if we’re looking at the actual low-reliefs. Regarding the ostrich, it disappeared definitely from this region in 1941.

Tree of life : “Yahweh planted a garden eastward in Eden and there he placed the man that he formed. And out of the ground had Yahweh grow every tree pleasant to the eye, and good for food. And a river went out of Eden to water the garden; and from thence it was divided, and became the spring of four rivers: the name of the first river is Pischon,… the name of the second is Guihon,… the name of the third is Hiddékel, which flows toward the east of Assyria, and the fourth river is Euphrates. (Genèse, II, 8-14.)