The simplest explanation, the most plausible

Well...Pictograms display the Engineers worshiped by men. These Engineers were pointing to the 6 planets system. Undoubtedly Engineers are the space jockeys. Their uniform for space travel is what is shown as an sj in the canon scene. Something like an exo-sceleton. So Space Jockey is the giant Engineer with a space suit. No other life form that would have to look like the elephantish look of the sj space suit. Engineers at first seem to be creatures of good intentions, judging from the pictograms. Even if gave birth to the human race, they wouldn't be really looking forward to their destruction... (or so it appears). Now comes the part "a King has his reign and then he dies...it's inevitable" . Now was that Mr Weyland's thinking or not? His reign on Earth would really come to an end at some point. So he was trying to find ways to become immortal? But this could also be the thinking of the sjs. Their race could be coming to an end.They also had to do something about this. On the other hand we find all sjs dead on Prometheus. Something must have eradicated them. So how does Weyland think they hold a secret to immortality? Perhaps sjs race has found a way to immortality by mixing their DNA with the indigenous DNA of the creatures on that 6 planet system....yeah I know...a dismay to all of us trying to find the exact origins of the Aliens.Since their race was coming to natural end, they developed a nurturing relationship with xenos. They would actually cultivate them to use their DNA for keeping them alive. At some point they lost control and got eradicated by the xenos. So the Promethean fire, is contained into these egg-shaped containers...The viscous liquid in the translucent bags that Fassbender tries to pull out in the trailer.Needless to say that Mr Weyland gets contaminated at will to transform later to an Engineer. The liquid is a liquid DNA mix that can transform a human into an Engineer to take care of the preservation of their race. So as he gets contaminated, even his conscious changes to the Engineer thinking. Whether it is Mr weyland or any other of the crew, that blue guy, becomes a true Engineer, and as preserving the continuation of his race becomes the ultimate goal, he prepares the ship for Earth, since LV is already a liability, and he has to deliver the DNA to Earth to bring back to life as living Engineers, the rest of the egg-shaped material, by polluting Earth inhabitants...Perhaps, in their previous journeys to Earth, they had found that only the human DNA, is most suitable for their revival, and they are not so good characters after all, and even further, they are not Gods, they have not created us, they just manipulated us to ensure the continuation of their race. That's maybe why we were so wrong. And no other life form was found by the sjs to match human DNA in terms of compatibility for their revival.No other creatures have fallen into the same trap as Prometheus's crew.It was always a trap meant for humans. So Mr. Weyland is our Prometheus, punished at the spot, believing that he could use the DNA secret unharmed, only to end up a vessel of the existence of an Engineer that consumed him. Also, explaining the other ship on LV-426, you can see in the trailer, there is a portal scene. Maybe the two ships communicate through that portal, and the one on LV-426 is the one that found the indigenous life form, while the cave on LV-223 whatever, is used as the base and laboratory for the sj race preservation. That's it, said it.Period.Shoot me!Or shue me!