Help? Found a baby bird; should I be doing something? Update 2

Hi! There’s a baby bird in my yard. It’s about the size of my fist. It has a few short white feathers. I think they’re pin feathers. The nest is too high for me to reach; so I left it alone on the ground.

More importantly and the reason I’m reaching out, the little thing hasn’t moved. It doesn’t move when I approach and it hasn’t moved from its spot all day. I don’t see any blood, but I also haven’t touched it because I didn’t want to distress it further. I haven’t caught the parents caring for it, but I did see adult birds in the tree.

Is there something I should be doing here? I’m leaving it alone and keeping my cats away from the window. The area it is in is shady, but it’s so hot outside. A cup of water? Should I make it a comfy box? I’ve got an ant problem in my yard. Will they hurt it?

Picture:

Update: I made it a “nest” on the recommendation of google and the wildlife volunteer that called me back. It hated it and ran away in small circles. After shooing it back to its original hiding spot, I left the “nest” where it could reach it if it changed its mind and fled the scene. At least it isn’t hurt.

Update 2: it was very chirpy this morning and I heard its parents so I chose to leave it alone. The chirping stopped this afternoon and, after a while, I went to check on it. It was dropped over and unresponsive. It was in the shade of the fence but I think the 105+ degree heat got to it. Thank you all for your input. I’m sorry I couldn’t do more… :(