I agree...childhood is a wonderful, amazing thing. It's pretty awesome being a dad to a small boy! It's...just...wonderful to watch how much fun a small boy can have with, well, just the simplest of amusements. Upcoming for this summer for your son might be something we did with Spencer: outside, an arrangement of at least two plastic, handled pitchers, a pair of plastic funnels, and a whole mess of cups, tiny buckets, plastic jars of different sizes, and a supply of water, either from a slow hose, or a large bucket or flower planter filled with water for "dipping" and "splashing"... watch as the kid spends hours on end pouring water from one vessel to another, building skills and strength and dexterity...then watch as Grandma and Grandpa are ASTOUNDED when the kid can pour four 12-oz glasses of milk out of a one-gallon milk jug and not spill a single drop, all by himself.
It sounds weird, but pouring water with this kinda setup is a FUN PLAY DATE for two or three kids!
One summer the kid learns how to pour water and has a BLAST!!!! Next thing you know, he can pour liquids at age 3. Kid wants a drink of water from the fridge? He can do it himself!!!