I think you understood most of it even while being confused about a lot of it lol. You even predicted the plot twist. I figured the part out about Shanshan that we were talking about in the Discord.
Essentially, they created a paradox where she survives because they challenged the killer and told him not to harm her. He took the bait cause of his ego. And I don't think we're supposed to know who the red eye person is right now cause even I don't know if it was actually Qiao Ling or if she was being controlled (haven't watched season 2 yet).