It is theologically tenable that Creation and Incarnation of the Second Person of the Trinity was willed by God from the beginning since this is how he willed to communicate his love toward his creatures, even if man had not sinned. But, since God knew from the beginning that man would sin, the Incarnation from the beginning was willed as a Sacrificial offering to the Father. Since the Incarnation is a once-for-all event, we can infer from this, that if there are other embodied spirits in the universe, they would also have experienced a fall from grace. This brings us to the question of Original Sin.
The depiction of man's fall from grace constitute only one man and woman. According to Church teaching, although it is not defined, we have to maintain that there was only one man and woman in the beginning from whom the rest of humanity descended. Now, if we find other intelligent life forms in the universe which also have experienced a fall, how are we to explain this unity? It may be that the unity of all intelligent life resides in the fact that we share the same nature, we are all embodied spirits with intelligence and free will. The Church insists that procreation is the only way of passing on Original Sin. If this is true on earth, it would also be true on other planetary systems.
Is this hypothesis correct? Only time will tell.