Actually, no. The common ancestor is neither hominid nor ape. Darwin never said we came from apes. I think what you meant to say is that the common ancestor is primitive and that apes are primitive, therefore it must be more ape-like than human-like. Apes are not primitive. They have very complex bodies and brains, just as we do. They use tools and can be taught sign language.
Tolkien did more than just write the Hobbit and Lord of the Rings. He was a professor who emphasized the study of the epic. In fact it is due to a lecture he gave in I believe 1936 that brought Beowulf to the forefront of literary studies, which has had a lasting impact. He is also responsible for creating an entire fictional language (elvish) that is loosely based on Gaelic and Welsh, which he started working on when he was a child. The world building was only actually done to have a place for elvish to exist. That said, I do find LOTR a very difficult read due to the archaic forms he used, and I don't think its Noble Prize material, even if it did start the fantasy genre. Several of the characters are rather flat, with only Bilbo, Frodo, and Aragorn really being round characters.
The existence of extraterrestrial life is completely philosophical and hypothetical. Saying that such-a-such scientist does or does not think there is otherworldly life is not proof one way or another, even if that scientist is decorated or the great Hawking, whom I admire. We can discuss the size of the universe, the number of stars and discuss it from a statistical point of view. The math involved does lead to the probable conclusion that extraterrestrial life must exist, but this is again not proof. As for the idea that "galactic spanning civilizations" must be seen from our small rock is human arrogance. There is a strong possibility that such a civilization exists and our current technology simply cannot detect it. As for question of celestial bodies and stellar objects being life forms, we don't know that they are non-sentient. that is a philosophical question of another kind. What definition of life do we use?