Lament all you want about the prequels but to say they brought nothing new is demonstrably false.
1. Bald albino engineers that seed worlds with life or destroy to create lifeforms.
2. The pathogen
3. Charismatic, fascinating, creative, sexually neurotic android ascending to God-hood
7. Fungoid egg sacs from yuggoth/spores
11. Hammer horror/romantic literary influences
14. New xeno design/chestburster/subversion
15. LV-223/Planet 4
16. Giger Li I tribute with Shaw's fate
17. Bleak misanthropic ending