I don't think they're meant to be alive. It's not acknowledged by the story, nor does it make sense.
Why would someone just drape themselves over an edge railing several stories off the ground that leads to death and just stay there? How would they survive that kind of gunfire and just breathe? If there were survivors, Cloud and the others would have said something to them or at least acknowledged them, just like they did with Biggs and Jessie.
Like, the system used to plant these "corpses" here are essentially to make them non-interactable NPCs who are silent and fixed in a position. They're not specifically made to be corpses. They just took a random person, spawned them on the field there, put them in a "dead pose" and then called it a day.