A very good movie....will be appreciated with time
Just saw the movie again after 3 years. It was really fresh and an enjoyable experience.
I disliked it when it was just released but I realize now that the reason was because it killed Shaw and negated the exciting adventure of Shaw & David set at the end of Prometheus. Also, it felt very uncanny at first to see David suddenly changing outright villainous as compared to the grey character of his in Prometheus.
But one little thing helped me recently to view the movie differently and it was a short film: 'Alien Alone' https://www.youtube.com/watch?v=ApNPbQxMFtk
Simply, its about being given a 'Purpose' to a Robot.
Anyway....I would like to state some points of my theory which can help understand the movie better.
1. From the deleted scenes we learn that David on Engineers' spaceship, tried to learn Engineer's ways...their purpose & methods. He has already seen Engineers' hatred towards Earth humans which he finds as a common attribute. He develops a god complex and similar to Engineers...he too want to create & destroy.
2. Planet 4 was not a homeland of the Engineers. It was just a planet terraformed by the Engineers and seeded with life but much recently than what they did on Earth. Hence we see humanoids on Planet 4 living in roman-era kind of primitive habitat.
The engineers on LV-223 had set each of their spaceships to several planets where they had seeded life and wanted to destroy them all. One of such spaceship was the one which was set to destroy life on Planet 4 and the one in which Shaw & David took off.
So eventually, they landed on Planet 4.
Perhaps, the Engineers world was devastated by some human race which they created in some altogether different planet and who got highly technologically advanced and waged war with the Engineers and its after this, the Engineers decided to destroy all humans they ever created terming them as their flawed creation.
3. Enroute Planet 4 , Shaw falls sick and dies. David unleashes the Black goo mutagen and kills the humanoids just how the Engineers intended to do. He crash lands in the forest and some of the remnant Black goo spilled and went flowing down mutating spore producing fungus growing on trees.
4. David tried to revive Shaw (the only human he loved) in his way but wasn't successful. He cracks and goes on a quest of 'creation'.
He sets the SOS on the spaceship and lures possible travelers. And voila, he got lucky with Covenant carrying 2000 colonists.
Please see the movie considering above premise, and things will start to fall in place & make sense.
Just a side note: Xenomoprh lifecycle was never created by David. He may have created the variant of Xenomoprh which we've been seeing in all other Alien movies but not the lifecycle because the lifceycle (Egg to facehugger to Xeno) was seen on the Mural in Prometheus so it existed much before the events of Alien Covenant.