Ah thanks for that last comment I did wonder if the arrival of the school hamster is what put him off and changed his behaviour
Do you know the dimensions of that cage? It looks fine for a young hamster but may not be suitable into adulthood. Most certainly the wheel will need replacing with a bigger one. You probably know from keeping rats that they need to be able to run with a straight back in the wheel or it is too small.
I would definitely put some more toys in the cage for him, and also a bigger house. It that tiny blue thing his house? Try just an upsidedown cardboard box with no floor-- I would also suggest adding a lot more substrate so he can burrow. That cage has a good deep base for lots of substrate. The box will get destroyed (chewed) but is easily replaceable. A tissue box maybe?
You mentioned seed and fruit sticks. I'd be careful with friut while he is likely still stressed from moving--you don't want to encourage diarrhea but a small amount should be ok. Be careful what you use to hang it with as it is likely to get chewed so you only want safe chewables always. Also I would be careful to hang it so he cannot get a foot or head stuck.
Also I cannot see clearly but it looks like you may have what's called "fluffy bedding" in there? If so, it needs to be removed asap--it is very dangerous for hamsters and can cause serious injury should they get a foot tangled up. It is outlawed in Germany I believe and there are efforts to have it removed in UK also.
Are you familiar with "whimzees"? They are a popular hamster chewable. You could add a "bendy bridge" or even just some toilet or kitchen towel cardboard rolls for him to run though. Don't worry about the shelf for now, hamsters need lots of ground room more than shelves like rats or gerbils. Egg cartons with holes cut in some of the egg cups put in upside down are a great hamster toy. I would hold off on the hammock for the moment until you see what kind of a chewer he is-- he can get into trouble with hammock fibres if he chews similar to the fluffy bedding issue.
The blanket was a thoughtful idea just be careful he cannot pull it through the bars and chew it-- same issue with fibres and some synthetics can be harmful if swallowed. That bar spacing looks nice and narrow but never under estimate a hamster determined to chew.
Try some scatter feeding when you get the tubes and egg carton in-- hide bits of food for him to find. Foraging is a natural behaviour. The down side is it makes it difficult to see what he is eating, but I think you want to encourage him to wander around right now.
I know you have gotten conflicting information-- that's one of the problems with the information on the internet there is no filter. My view is that you want to try and create as natural and comfortable an environment as possible. When your hamster is comfortable he will naturally be more friendly and you won't need to resort to harsher measures like removing his house.
I also suggest you all do the tissue trick. Put an uncolored, unscented tissue up your sleeve for half a day or more. Then shred it a bit and leave it in the cage for him to use as a soft liner for his nest. It will help him get used to your scent.
Let us know how you get on and post some pictures when you get the toilet rolls etc in.
ETA I doubt the blue light is an issue.