The Continuity of Alien is messed up beyond repair

On its way back to Earth after a mining trip, the starship Nostromo picks up a distress call from a nearby planetoid emitted by a spaceship created by a race of giant, bald albino humanoids who visited Earth in prehistory to create life on our planet by means of a black mutagenic pathogen which transformed the humanoids' DNA, giving rise to myriad life forms before leaving behind murals and cave paintings inviting humans to come and visit their creators on their home planet, prompting an expedition from Earth thousands of years later that takes the crew of  the starship Prometheus to the aliens' home world, which isn't the aliens' home world but a munitions factory for creating bioweapons in the form of a second black mutagenic pathogen which gives rise to hostile and parisitic life forms resulting in catastrophic loss of life for  the humans exposed to it and eventually producing a creature resembling a crucified figure on a mural created by the space giants thousands of years before said creature ever appears. The crew of the Nostromo set down on the planetoid and find a cargo hold full of eggs belonging to another parisitic and hostile life form engineered into existence ten years earlier by the severed head of an android who had his head reattached by the sole survivor of the ill-fated Prometheus expedition and who returned the kindness by murdering her and a city populated with technologically backward giant bald albino natives who may or may not be related to the space giants who created life on Earth and the pathogen encountered by the Prometheus expedition. The android uses the pathogen to create a monster he names the "perfect organism", despite its need for the bodies of other pre-existing life forms to latch on to incubate its offspring, before heading off to a human colony to continue his experiments with the result of his experimentation somehow ending up on a fossilised spaceship estimated to be thousands of years old by the crew of the Nostromo when they find it. The human personnel of the Nostromo take a monster on board their ship where it kills them one by one until the last human survivor blows the ship into atoms and blasts the monster out of her life-pod where it dies in the vacuum of space, only for a team of scientists from Earth to wander by years later and take custody of the dead but not dead monster and use it to reverse-engineer the black mutagenic pathogen developed by the giant bald albino humanoids, producing a sample of the pathogen which is then injected into a pregnant woman who gives birth to a hybrid child that is half monster and somehow half the giant albino humanoid species that created humans.