I've experienced depression when the symptoms are quite severe and debilitating. When it feels like that, it's almost impossible to feel what I would call "normal".
When I'm not feeling the depression as much, I usually don't struggle as much in seeing humor in everyday stuff, even in screw-ups, difficulties, minor inconveniences, major episodes of whatever sort, etc. However, when I am more acutely depressed and having difficulties in just carrying on with my normal everyday life, my sense of humor or lightheartedness is locked away - far farrrr away in some secret locked drawer.
I observe other people (out in the world, in stores, on television, wherever) & wonder how they can be so happy and sometimes even perky. I mean, maybe they are happy, maybe they're struggling just like me - not sure. In any case I find myself wishing that I could locate my normal contented relaxed happier self.
And then sometimes I just accidentally (magically almost) think of something silly or somewhat humorous (truly a total accident in these cases), & I might say something aloud to someone or not. Don't know where I find that "place", but it kind of saves me in a way.
Also, each day I try to take part in at least some of the things that I'm "supposed" to enjoy, or have enjoyed in the past. Sounds odd I know, but I have to kind of force myself to be involved in more positive tasks. Even if those tasks are part of mundane daily routine jobs around the house. I try to point my thoughts in a more positive direction.
Not easy.