Rescued Ringneck

My little sister found an almost full grown ringneck dove on the street on her way home from school a few days ago. It was in the middle of the road and would've been run over if my sister didn't go get it.
I'm not sure what's wrong with it. It has all its feathers except for a few little bald patches around its beak and neck. Its been showing signs of distress, making the little "hinnnh" sound and it's feathers are always fluffed up and it's head down. I'm guessing its because of being around humans
The only reason we've kept it is because it can't fly and there are SO many cats around our apartment complex. We took it outside one day to see if it would fly away but it will just fly from my hand to the ground. Not even really flying, its more like gliding to the ground. We put it up in a tree to see if it would go off on its own but it just stayed in the exact spot we put it. So we took it back inside.
It's been drinking water and eating the seeds were giving it.
Does anyone have any advice or experience with a dove like this?

Keep feeding and taking care of him and maybe he will recoup and get normal/healthy. The fluffed feathers may mean he is cold. Birds fluff feathers to create better heat retention insulation. I'm glad you took lil guy in.
I personally would do just as you did. I also have pigeons, so would just let him hang with the flock. When he would be good enough to fly away, I would let him go then. Doves would not return to my loft like my pigeons do.

Hope he will be okay