I completely agree with you when speaking about the the first two movies. But those two never explored grander themes such as creation, life, good, evil, presence of God, etc. Those two focused more on a monster than on those greater questions.They roughly tried to mention such questions but monsters, killing and fear were more important in all Alien movies (Story of monster in tin can is now pretty much worn out). QUESTION OF PURPOSE and MEANING was marginal! Prometheus introduced those questions, but failed to answer any of them... I hope Covenant is about to clarify some of those grand questions. I even don't expect full simple minded answers, I myself want mystery, horror and some big things that can in some way clarify the existence of Xenos. Why Xeno? Why black goo? I dont want Engineers running around and killing I want to know their motifs no mater how strange they could be... Xenos are monsters (bioweapon), but monsters can have larger meaning and purpose other than killing and being monsters. Monsters and bioweapons are made for something and for someone, isnt that true? Why would "GOD" create such organism, and if not God, then who? Why would humans create androids and why would Engineers create humans? Is creation alone enough to someone become God?
I belive that the story of Engineers and their relation with Xeno could be epic. Covenant need right balance of
some answers and mystery, and everything will work. Humans and David as human creation, must play a vital part in whole story of Xeno existance.