He didn't have a health bar...
(Context- I went off to explore a recently cleared cave while everyone else looted and took a short rest, and decided to ignore literally everything I saw because I thought the DM wasn’t paying attention)
DM: Oh and by the way your Fighter sees a man bound and gagged laying on the cave floor.
Everyone else: Why didn’t you tell us?
Fighter: I didn’t think it was important to mention so I just walked away
DM: How did you think he wasn’t important?
Fighter (OOC): He didn’t have a health bar