It goes way back to 1979 when the work of Ridley Scott is enjoyed and is a greatest determinant of the franchise success. In Alien (1979): as they are returning to earth, a sudden mysterious transmission is witnessed, the company policy orders for an inquiry into the matter and so, they land on the planetoid after having sustained some damages.
The crew of seven members includes, executive officer: Kane, Captain Dallas, Science officer: Ash, navigator Lambert, warrant Officer: Ripley, Engineer: Parker, and Technician: Brett. As some are repairing the ship,
Looking closer, there are things like eggs in the back and one of them opens up. Dallas and Lambert carry Kane back to the ship, but Ripley refuses to open for them. As others plead, he finally opens and they are let inside.
This becomes the beginning of a major way on the ship as the organisms grow in them and others attack them causing havoc at the ship. Aliens declare war on them, making them blast themselves in order to kill them. As all this happens, they are recording a video that will be a witness once any of them survives.