That may be because his desire for the food is stronger than his fear of your hands ha ha.
Don't worry- you'll get there. Give him loads of substrate and just spot clean mainly - they will also use a litter tray which meansthe cage stays clean and dry andyou just empty the litter tray every 5 days or so. They will use it but only if you put it in the right place
ie the place they decide it should be (often corner of the cage where they choose to pee).