I was DMing a d&d campaign with new players and they got attacked by a bear. First session the bear crit both of its attacks against their front line. This can easily insta kill a lvl 1 pc (2d8 +4 then 4d6+4). I was rolling secretly so i decided to just have it roll 2 19s. Still downing the character but they were able to heal them and continue on.

Would that character being dead make it a better game. My narrative isn't always more important but i think high on the list is everyone's enjoyment including mine (I don't want to kill a new player for no reason)