They go through a huge fussy stage - I'm sure a big part of it is about exerting their will, and learning about what happens when they refuse to eat!
Definitely keep offering previously rejected foods, and keep and keep offering (especially if they are 'staples' for your family). Even if he never ever eats them, they will stay familiar and chances are he will give them another try.
Keep portions really small, they are easily 'overfaced' and it is better to finish off a tiny portion and then have another helping.
Oh the other thing is, if he eats something 'new', serve it again very soon afterwards and keep it in heavy rotation so that it stays on the 'will eat' list. My LO hated potatoes until he turned 2, he loves mash now.
Frozen blueberries, cubes of ripe pear, you can experiment with different shapes too.