What possible value could depression have?
> Another reason depression is thought to be a pathology is that key symptoms, such as loss of interest in virtually all activities, are extremely costly to the sufferer. Biologists and economists have proposed, however, that signals with inherent costs can credibly signal information when there are conflicts of interest. In the wake of a serious negative life event, such as those that have been implicated in depression (e.g., death, divorce), "cheap" signals of need, such as crying, might not be believed when social partners have conflicts of interest.
https://en.wikipedia.org/wiki/Evolutionary_approaches_to_dep...
I dont know, IANAD, but it sounds mildly plausible.
Literal survivor's bias. If you are depressed but not resilient, you kill yourself.
> learning to overcome adversity, learning to overcome yourself
Overcoming adversity requires doing something. Depression prevents that.
> learning to be self-aware
I wish.
> thinking "differently".
In what way?
These sort of ideas are hard to evaluate definitively, but I do think it is plausible that mild depression had/to some extent may still have benefits. Of course certain traits can be taken too far though, and when viewed through that lens it is hard to understand how they could be beneficial at all. One could say a similar thing about Autism-like traits.