My son naturally loved to play with his food, too. I just fed him the finger foods myself for a while, wondering the entire time why he wasn't doing it himself, until my mom suggested I show him that he could pick it up himself. So I started carefully putting a cheerio between his finger, showing him that he could hold it. I actually had to move his fingers and hold them around the cheerio, guide it to his mouth, and then release his fingers. It took some patience, but once it connected in his brain he was feeding himself just fine.
Same with his sippy cup; I had to put his hands around it and hold them there, and help him tip the cup up so he could take a drink. He didn't like me holding his hands still at first, and fought it, but once he figured out he could take a drink by himself he never looked back.
Kids don't know these things naturally; some figure it out on their own (my nephew), and some need to be shown and taught (my son).
Just make sure you are slow, patient, and keep a smile on your face and a sweet tone to your voice (as he is sure to get frustrated a time or two), and don't expect it to happen the first time.
If nothing happens after a month, then go to the doctor– not on a "something is wrong with my son" trip, but to ask some questions and get some answers. But try this first. It worked for my boy. :-)
God bless!
M.