I can't stand humanity or life in general at times. is this a symptom of depression?

Hmmm: Could be. But, the main symptoms of depression are sadness & inability to enjoy life, which you did not describe. Sounds more like you are disappointed in people and that has made you mad & bitter. Freud once said something like ... It is not surprising that people act like animals (since we are animals). It's surprising when we don't (i.e., when we are civilized, kind & generous).