So far we're lucky and we have a little girl who loves to eat just about anything but I know I was a very picky eater when I was a kid. I wouldn't eat any veggies aside from potato, very picky with meat and how it was cooked, only ate apples, bananas and oranges, milk and cheese were fine but no other dairy and salad was never going to happen. This went on for years, well into me being a teenager. I never really had a problem at home cause we were a meat and 3 veg for dinner every night kind of family so I'd force down the other veggies with mash potato. Now as an adult I've become far more adventurous and there's not much that I won't at least try. I love all kinds of foods, even the stuff that I genuinely hated (as opposed to just deciding I didn't like it) as a kid.

I think it's probably a good idea to check out any possible sensory issues, but otherwise so long as he's getting in stuff from each food group and is eating enough, I'd just go with the flow. Certainly encourage trying things, but pushing it could make it worse.