You are the director!

Well if i was the director after the first film i would first go back to the drawing board and try to design the alien that was Gigers original necronomicon 4, with the huge eyes, and almost human hands, with a sickly mushroom colour texture. I would add additional features such as the ability to Camouflage its self like a chameleon, or a octopus, that can communicate through pheromone's and patterns on it skin. The premise would be to have a team of explores on a expedition to search for valuable resources (nothing new here ) but feasible enough and by accident come across the alien sj home world. Here they discover that this species is highly organised and structured unlike anything they have encountered before a bizarre mix of social, yet sophisticated intellect, where they have used the sj to serve as their guardians, and protectors, almost like worshipping, and catering to their needs from space travel, to environmental manipulation, and social structure. On learning that there world has been discovered by Extra-terrestrial beings the xenos, and sj, track down this species and make attempts to communicate. It becomes clear to the crew that the alien xeno is not malevolent and uses a host body as a way of replication nothing more yet on the home world this process is done by selecting various species native to that world. After sometime of learning about the two dominate species the xeno, and sj it becomes apparent that the crew have started to become infected with a virus of some sort simply by being on a biological alien world and the virus is working at a molecular level, altering the human dna and causing it to begin a metamorphosis process. On learning this they decide to leave and head home to earth where this virus is becoming more and more aggressive, to find a cure or something that will reverse the process.The virus takes the form of an erotic unbearable craving to be in the presence of the xeno and it appears it has effects similar to heroin addiction but stronger still . All the while the effects of this are rapidly altering the human biology Unbeknown to the humans this has been having a similar effect on the xeno's but in a totally different way and this is the catalyst for the xeno to instruct the sj to hunt for the human home world and try to find a cure for this increasing virus on both worlds. Eventually the sj find earth and fleets of ships are infiltrating the corners of the globe where instead of being met with violence, and defence, the species of sj and xenos are met with ecstatic relief, and exuberant joy, this feeling is reciprocated by all sides and eventually a symbiotic harmony is reached between the worlds and eventually the whole planet had metamorphosized into a completely new species, not through sex, or manipulation, but through some Pheromonal bizarre side effect of contact between two alien species. Eventually the planet earth is inhabited by a species that has no resembalence to the lifeform previously known as human beings. This life form is of a higher order and has no need for war, or famine, or suffering, but has taken to the prospect of colognising the universe ., The new order does not call this process evolution but refers to it as xenolution. scholars of the new world wonder if the process is by fate, or design, and this is the beginning of the new age. Complete bollocks i know but hey you asked lol.

I think that Alien and Aliens are indeed untouchable to the whole Story i dont think many would have wanted to had changed them. Maybe in Alien 3 or 4 we could have then found out about the Space Jockey? But i am guessing that the idea in Alien behind him was he was the last one of his kind and thus nothing really would have been found out, especially as LV 426 was nuked at the end of Aliens. So a Prequel would have been the only logical way to answer the question who was the Space Jockey.