"Having different kind of Xenos is something that I like but then you can wonder how come there are different kinds."
I think this just shows the constant evolving and changing of the Plot/Story.
Alien Engineers we see the Engineers have been Creating and Experimenting with 7-8 different Versions of the Xenomorph as a Bio-Weapon, while a bit ambiguous it appears to me that there may be a Native Organism from LV-426 in that Story that the Engineers had Experimented with to Create the Various Xenomorphs. The Method used to Create these Hybrids was likely the Urns.
So i ASSUMED.. from reading a number of times Alien Engineers.
*The Organism Holloway is infected by is something the Engineers had encountered and witnessed the results of its Life-Cycle. They then tried to Re-Engineer this Organism into a Bio-Weapon.
*The Urns Fifield Runs into contains the Scarabs that have consumed/obtained DNA related to the Xenomorph and thus its likely they used the Sacrificial Scarabs on the Organism they encountered to attempt to Engineer the Perfect Bio-Weapon.. just how David had done so with the Black Goo and his various Experiments.
WHILE Prometheus Toned down any Xenomorph's there are clues there that suggest similar had been going on at LV-223, and we have to Ponder do the other Temple mounds Contain different versions of the Black-Goo and thus Different Strains than the Deacon one?
ALIEN COVENANT has shown us that the use of the Black Goo can be used to create a large Variety of Xenomorph related Species.
So the potential/likely hood to explore various related but different Xenomorph/Deacon/Neomorph Type Organisms is HUGE.
