My daughter didn't really take to baby food until 6m. Then it was only when Grandma would feed it to her. For me, it was probably closer to 7m before we really got things down. Then she went straight through the baby foods to stage 3 foods and finger foods. She prefered foods that had texture and crunch.
For cereal, have you tried just one type or many? My daughter loved the rice cereal, but wouldn't touch the oatmeal!
When you sit him down to eat, is he at the table alone or with the family? My kids always ate better if there were people around the table.
Something to try is to make baby food popsicles. Place the baby food into ice cube trays, and place a stick in the middle. Freeze. Then when its time to feed, just pop out a few cubes. Baby then naws on the cube.
Another suggestion is to offer him low-salt crackers or toast. Not burnt, but stiff.
M.