At the time 'Alien' was made, it's absolutely clear that the eggs were intended to originate from the derelict occupants. Lamberts throwaway "I wonder what happened to the rest of the crew" line, the fact that everything we see on the derelict foreshadows what will happen on the Nostromo; the hole in the Jockey's rib cage burst outwards (as per Kane), the acid burn on the floor by the Jockey (as per the Nostromo infirmary when Ash attempts to remove the hugger), and at the time of filming, the egg morphing scene, which shows what happens to the crew the Alien takes.. basically the Nostromo was becoming the next derelict, a ghost ship that could later be discovered with several eggs in the lower decks, had Ripley not detonated the engines.
The queen is absolutely unnecessary, and the alien was a better creature without it.