Hi,
Food transitions with kids take time, please try giving him only 1-2 new things each week, if he does not like it that week, give it to him 2 weeks later again. It takes a number of repeated tries before they enjoy something since their taste buds are still developing. Also increase the gap between his meal times, he will eat better when he's hungry.
Is he stilling up in the high chair? If yes, serve food on the tray itself and let him explore his food with his fingers. Plate/fork/spoon throwing is a game he enjoys probably, along with your reaction. Its OK if he makes a mess while eating.
Sometimes kids appetite changes as well, and they eat more during growth spurs and less otherwise.
N. P.
California