Food and toys are a commodity for dogs. They value and have an innate desire to protect it. Your puppy needs to learn that his food is your food and you allow him to have it.
when you feed him, make him wait to eat. Fill his bowl and hold it. Make him sit. Place the food on the floor and tell him "wait". If he gets up and approaches the bowl sit him back down and tell him wait. When he relaxes and looks at you for permission then tell him "OK" and let him eat a few bites then take it away again. Repeat the process.
also, he eats after you eat. Breakfast lunch or dinner, it doesn't matter. A food agressive dog must understand he is at the bottom of the rescource chain. Same with snacks and begging at the table. Send him away. Do not allow him to drool over you while you are eating. Make him lay in the corner or in another room. And dont just shut him away. MAKE him lay down and stay away while you are eating. He will associate this command to you are in charge of food and he doesnt get to be near food unless you allow it.
learning that you control the food and that he eats at your discression will curb the food aggression behavior. And it IS food aggression. He is young and that's why he's not behaved this way before.
Toys are no different. You need to teach him to give up his toys whenever you tell him to. We use the command "drop it". You need to be able to remove anything at any time from his mouth with out him fighting you. If he has a toy, you tell him "drop it". He will fight as he learns. Do not play tug-of-war with him. Its not a game. He must not be allowed to think its a game. You may need to use a leash at first so he can't run away either. If he growls give him a firm "no"! And then repeat the command "drop it" while you have your hand on the toy.
It can be scary to have a large puppy growl at you, but you MUST get back in control of him before he gets larger. And the WHOLE family must be able to remove food any toys without fear of being bitten. Once the adults have mastered the food and toys then supervise the children doing the same. He must know at all times that he is at the bottom of the pack.