I have had my pembroke welsh corgi for a couple of months now, he is 5 months and I have noticed when I try to take something he is chewing on ((chicken bone)) He snaps at me and tries to run and hide the food. Other then that he is very happy and loving minus the puppy chewing on you.
My GSD/St. Bernard mix did that when he was aabout 3mo old. I started stepping on the bone and blocking it with my feet before I tried to pick it up. I did this with every toy and bone he had. I also stuck my hands in his food before I gave it to him so my scent was on it, and when he didnt have a bone, I would pet him and check his teeth and gums along with brushing his teeth so he got used to my hands being in his mouth. He is 10mo old now and is fine, I will stick my hands in his his mouth if he picks up a rock or stick on our walks and he is fine.
Also try feeding him his dry kibble meals, by hand for awhile. That alone can change the whole concept in their minds that you are a threat to their food. If you have other dogs as well, they should be fed sperately in their own crates to avoid fights.
After you have fed the dog their meals from your hand awhile, then start taking their portion and dropping it one handful at a time into their dish until the portion is gone.
Work to the point that you can have your hand on the edge of the bowl as he eats, then so you can touch the kibble...not take it away at first, just be able to reach in and remove your hand without him growling. If he back slides and starts to get aggressive again, go backward to the last successful step he had completed and go again from there.
Bones, rawhides, etc will be a special challenge. Teach him a 'leave it' command expecting him to not take or touch whatever it is he wants until you okay it. Always give treats and similar extras straight from your hand, not just tossed to him. He has to learn that you are the one that is in charge and make him learn respect. Mine are taught 'take it nice' so that I am not having to count fingers after each treat, lol.
Life isn't about waiting for the storm to pass. It is about learning to dance in the rain.