You're not an idiot, it's just that Alien's strength is its mystery. As hallowed and revered as Cameron's sequel is, even that film degrades the first's perfect unknown. Every following explanation has been a dilution of the initial incredible idea. Basically, you're not stupid- it's just that literally every answer pertaining to the eggs and giant pilot carcass found in the first ship will be totally lame compared to the mystery of never knowing. It's an alien- pure predation without thinking or guidance, focused solely on consuming. Life cycles and origin myths- while interesting and pulpy- are lame compared to its central idea.
This is so true, and is really what has been sad about each subsequent Alien film, and why this new chapter in them is so misguided. The power of Alien was, in part, because the crew of the Nostromo peered through a keyhole and got a glimpse into a terrifying corner of the universe they cannot comprehend. In these films the door is flung open and....David is standing there.
I really love the original idea of Alien, filmed but not included, that some of the victims were turned into eggs, as part of the parasitic life cycle. An answer to Lambert's question, "I wonder what happened to the rest of the crew?" can be inferred from the vast egg chamber on the ship.
That means what happens to the Nostromo is an echo of what happened to the derelict alien ship. There, the parasite took over the ship infecting everyone, and the pilot was the last survivor, setting up a warning beacon to keep others away. It tragically had the opposite effect, drawing another crew near so they suffer the same fate. Ripley ejecting the alien from the shuttle at the end thus means both her survival, and the breaking of that cycle of tragedy.
It's just one possible interpretation - maybe the pilot was transporting the eggs for some reason - and it's based on a life cycle cut from the original film. But that's my headcannon for the original film, where we understand what happened - but are still no closer to understanding the alien itself, nor the space jokey or entire race on the derelict. Just that we stumbled into this far corner of the universe we are not at all prepared to understand or handle.