OP, DS2 is autistic and was like this as a child. We just had to be really patient and not make an issue out of it (I really do know how hard that is. It's frustrating and upsetting to have a child reject your home cooking.)
With a typical child, you have to introduce foods about twenty times before they try it or settle to it. With autistic children, or ones with similar sensitivity to texture, you have to introduce foods between 200 and 2000 times.
Stuff that helped us was:
Teach him the major food groups and explain why they are all really important. Explain which foods make him strong, make his brain sharp, grow his bones and teeth etc. I used to say, you really don't have to enjoy it, but if you can manage to eat it, it will help you grow strong muscles/bones/teeth etc. Explain why 50/50 white bread is better for him than plain white and suggest he takes one bite. If he can handle it, it;'s better for him. If not, no problem, eat white.
Put food from all food groups on the table and make dinners self serve. Just say - choose a protein, a carb and 2/3 of your 5 a day. Let him control what he chooses from each group, and what quantity he takes. Make no fuss. Then after a few times explain what quantity he needs.
Always have some frozen aisle rubbish standing by and get him to prep it himself as soon as he is old enough. he might get bored and eat what you make instead.
DS was so fussy that he was skeletal and barely ate for the first eight years of his life. (Affected his growth really badly, but hey, he's alive.)
Then he ate about six or seven things and nothing else for about four years. Then he suddenly got interested in food and started eating and over eating.
Now he's mega health conscious and really likes experimenting with food (he's 18.) He's no fussier than anyone else. It just took years and years of patience to get him to that point.