As much as I adore Cameron's film (it's in my top 10), it didn't do anything to add to the original work and departed from the original's artistic vision completely. For all intents and purposes Aliens didn't need Alien. Cameron could have done the same film, with really quite minor changes under it's own banner (and probably wished he had when Alien 3 came along and torpedoed *his* plans for the series, he didn't try to hide his rage either). Indeed, Aliens was simply the result of him wanting to do a big budget war film, but being unable to get funding to do it and Fox wanting to milk the success of Alien (concieved as a one-off). Hitching up his idea to Fox's moneytrain was the result
Cameron was decent enough not to openly shit all over Scott's work, but he never really intended to follow with the original vision. Aliens was all about him hi-jacking the brand, for his own purposes (for better or worse). He sidelined Giger completely, despite Giger being keen to get involved, having been a key creative element on the original (his involvement went beyond scultping the Alien). Cameron redesigned the xenomorphs and invented the new queen and hive, without consulting Giger. He threw the whole bio-mechanical vision Giger had drawn up for Alien out the window, the "perfect biomechanical stalker" xenomorph went out of the window infavor of "hivemind bug/fodder", Ripley also changed, a lot, etc.
I won't bother to go into Alien 3 and the abomination that was Ressurection, but they pretty much cement the fact that Alien, the franchise, is pretty much whatever the active director/writer/studios wants it to be, and thus as a series is worthless. Put simply: Unless films (or books, for that matter) are designed, from the outset, to be a series, with a well defined roadmap and the original creative team involved at some level, they really shouldn't get follow ups, particularly not gravedigs decades later. As to wanting to know what how the derelict came to be, etc, whatever happend to having a bit of imagination?
I'm sure most people have theories as to how events unfolded. This prequel won't reveal the "absolute truth", just some hack's interpretation of what happened, crafted to flog tickets, rather than being what makes sense, or originally intended (original writers aren't involved). For those that lack imagination (the shame): The Dark Horse comics/novels, which had some input from the original writers, dealt with the "Space Jockey" issue decades ago. Their interpretation is no less legit than whatever they cook up for this, imo. 'Canon' means jackshit when a franchise has no firm base and is made up on the fly, by whoever happens to get their dirty fingers on the IP.