Unless David went back in time, there is no way he CREATED the Xenomorphs... He could ONLY have RECREATEDthem if he had had a blueprint... Also, the eggs would require hosts AND going back even further, why 'EGGS'...? We know there has to be a Queen for eggs to exist (and no, eggmorphing has never been canonical, just a fan theory, never truly been addressed in the post-ALIEN movies, actually being flatout denied with the Queen in ALIENS and the superfacehugger in ALIEN3...) So, did David have a Queen to produce those eggs...? This is where the sequels and prequels create a mess of something that was simple and straightforward in ALIEN: the egg contained a facehugger that would deposit an embryo inside a host, then the embryo would gain some of the DNA traits of the host and after maturing, it would burst through the host's ribcage... the Queen was added later to be the one who laid those eggs, which made sense... Species do not exist in a vaccum, always being the natural evolution of a more primitive one... The issue I have with PROMETHEUS is that it flatout states that the Xenomorph is just a manifestation of a virus depending on that species it infects or it was spawned from... Clearly, all the xenos we saw from ALIEN onward were the result of the eggs from the Derelict... The Trilobite and the Deacon were not... Also, the egg-laying Queen who generated those eggs in the Derelict's cargo hold was likely the result of a combined DNA of an undisclosed creature with either the black goo or the spores, according to the Deacon's lifecycle in PROMETHEUS... The Neomorph in AC comes from a spore infecting a human host, the Xeno from a facehugger on a human host... I gather the biomech look of the Xeno in ALIEN would have to be already a trait of the Queen who laid the Derelict eggs in the first place... otherwise, they would look like the Xeno in AC... This is scientifically very confusing but equally fascinating....