We know the reason the Captain made some mistakes, he was obviously heavily fatigued after flying 8300 hours in 3.5 years. I think an extra 0 may be added there.
In the case of passengers and evacuations, they are frightened and confused, half of them already had bags out ready to disembark. The general rule I've always considered is people will get injured in evacuations, that's the risk of it, you can't expect the great masses to act like a bunch of crack soldiers when the alarms sound. Even trained professionals make mistakes, the average human is liable to do anything when suddenly startled into fight or flight mode.
Also the passenger that tried to re-enter simply walked back via the aerobridge, I assume most other passengers had walked off with their bags so its a pretty unusual situation for an evacuation. Probably though everyone else had their bags, I'll go back get mine, not realising it was a real evac.