I recommend you start offering him things directly from your plate. He is physically capable of eating just about anything now. And try unusual things you wouldn't expect a toddler to eat. He might surprise you. My kids love Gyros & tacos & Chinese food. They have been eating & loving these since they were about 12 months old. He might be looking for something with more flavor. Or he might just like eating off your plate.
Also, if you are not doing it already, give him a fork & spoon & let him try to feed himself. Or maybe he eats the foods he eats, b/c you still feed him those, but not the others. Maybe he wants you to still feed him.
Some other food ideas...since he loves cheese, try mac and cheese. Try pasta & red sauce (my kids love bow tie pasta, tortellini, ravioli, lasagna, etc). One thing that my boys really enjoy with their pasta...I bought a block of parmesan cheese one of those crank cheese grinders, like they have at olive garden. My kids will ask for seconds just so they can crank more cheese on their plate.
My kids also love to dip things. So if we give them chicken I will also give them some ketchup, honey mustard and/or ranch on their plate. So, they can choose their dipping sauce.
My youngest will only eat chicken if its mixed with apple sauce. He will eat steak or ground beef plain. But chicken needs something.
Also, let your son "help" cook dinner. He could stir something or pour something. My kids always eat better on the days they help make the food.
Good luck.