Hello, as said above, you'll need to remove the mesh wheel as it isn't safe for hamsters unfortunately. What species do you have? Knowing that will help us in determining the safety of some things as well as in directing you on what to get. The food seems to be alright quality, but really doesn't contain all the nutrients a hamster needs and also lacks severely in variety. The treats are safe as long as the only thing they contain is banana and alfalfa. As mentioned above, hamster balls really aren't all that good. In my opinion, they shouldn't be used at all. Hamsters explore their world by leaving scent trails and feeling things with their whiskers. Putting them in a ball completely takes these two things away from them. It's just no good, especially when you can instead offer them a playpen. Even just an empty bathtub with boxes and toys in it can make a good play area
I would fill the entire base of the cage with bedding if you can. Hamsters love deep bedding as they're burrowing animals. You'll also want to have a non-scented bedding as pointed out above. I'm not sure if the litter is safe or not. As long as it's a hardwood or paper based pellet that is non-clumping and has no additives, you should be fine.
Overall you're doing fine, you should just make a few changes and then you're golden
If you have any other questions, please ask