Here's what I would suggest. Give him his own spoon to hold while you feed him. You can put a little food on his spoon so that he feels like he's "feeding" himself. Put a little of the food on the high chair tray and let him mess with it; inevitably his hands will end up in his mouth and he'll get a taste.
Zucchini is kind of a hard food to start with, I think. My 8 mo. old eats all kinds of food, but she does not like zucchini. Try carrots or squash - those have both gone over really well with my baby. Other foods that have worked well for us: sweet potato, apple, banana, mango, peas, avocado, white potato. Also on the cereals, try thinning it out to make the texture more palatable. That was a problem for us when we first started on it.
And just keep trying. That's probably the best advice I can offer. Eventually you will find foods that he loves. Good luck!