M.B.
At this age my oldest son was a picky eater. The foods he'd eat (other than what you mentioned) pretty much revolved around meatloaf, nutrigrain bars or they also have these breakfast cookies and muffins in that same aisle, dry or cereal soaked in milk such as cheerios or Quaker Oatmeal Squares, toast with spreadable fruit or butter, cheese, english muffin pizzas ( I made these for him because the bread is soft and easy for him to chew at this age). That was pretty much it I believe, he also liked yogurt, peas and avacado as your son does. My son ate the baby food fruits until he was 2. He liked it and I didn't see any reason why not it was getting him to eat fruit in some form.
Since my son was a picky eater I fed my son the baby food fruit at the same time I offered him the small pieces of table food. I'd place a few pieces on his tray at a time and give him the fruit in between. He is now 3 and his eating habits have gotten better each year.
Good luck! I know its tough because sometimes you feel like they aren't eating enough variety but it sounds like your son has all his food groups covered and thats what's important.