Praise him every day for being creative. He's so smart that he's sorting everything in his world. He's so imaginative that he loves pretend play.
I get the feeling from the post that you and your husband might be worried that he's not "hitting milestones" that you might consider "normal boy things": Playing soccer willingly, being interested in bikes, playing with toys that are officialy "Toys" and not stuff he's picked up. He's already maybe beyond those things -- He will be the kid in grade school who is leaps and bounds ahead of other kids when it's time to start thinking spatially (great for math and science) and also when it's time to start thinking creatively (for language arts).
I would not worry about him but instead would encourage him by providing even more unusual things in his environment to explore. He needs stimulation beyond the traditional things! It's more work for you but both of you will love it if you think outside the box a little more....
Try him out on cooking with you. Do kids' science experiments (ALL over the web! He will love making goops and potions that do stuff and turn colors; make a classic "volcano" with him, etc.). Take him outside and make giant bubbles with a hula hoop (there are recipes on the web). Dunk marbles in paint and have him roll them over paper in a baking tray to make crazy patterns -- do lots of unusual crafts. Find tons of old boxes, get boxes from the grocery store, get out paper towel tubes and masking tape he can tear easily, and let him make giant robots and whatever he likes.
And definitely please take him to kids' plays and puppet shows because he loves make-believe and they'll fuel it and delight him.
In other words -- Bikes and soccer and toys aren't all there is to being a boy his age; go with what he likes, not with what he "should" be doing. He's just not interested in soccer? Put him into a kids' group music class or art class or "Mad Science" type classes where he can put cool junk together all he wants -- something more creatively based.
The issues of wanting your attention when he doesn't have it are very, very normal. He just needs time to mature. Same goes for the lack of interest in writing; ask his preschool teacher how to reinforce that -- maybe by having him see you write the grocery list, then put him in charge of holding it and "reading" to you from it through the store while you shop. Tell him he can help you write it next time. Give him lots of opportunities to see you happily writing things and asking for his help and ideas.