With simple language and repetitive phrasing, this guy’s not trying to make your brain hurt. In fact, he’s just laying out some images that he’ll return to, again and again, in an attempt to make the spring day as alive for you, the reader, as it is for all those excited little kids out there who get big smiles on their faces whenever they see a guy with a big ol’ fistful of balloons.
Have you ever listened to a three-year-old tell you a story about his day? He rarely stops to breathe, let alone pause when a sentence should end. The whole thing runs together into one big, happy muddle of a story. That’s sort of the effect that all those conjunctions (a.k.a. all those "and"s) have. It’s kind of like this: "So today at school the teacher let us make macaroni posters and mine was really awesome and it had a blue dinosaur on it and then Julie she’s the girl who sits next to me she broke mine and then I hit her and then she bit me and that’s why I had to come home early." Notice how we never slowed down there? That’s partially the effect that Cummings tries to create for his speaker. The words slosh together, running over each other as if they’re overlapping brush strokes in an impressionist painting (kind of like the paintings that Cummings himself created). Notice how often "and" comes right at the end of a line, creating an enjambed line. We’ll talk more about that in "Symbols, Language and Wordplay."
We say that speeding up is "partially" the effect that Cummings creates for his speaker because, well, there are times when the speaker slows waaaay down. Check out what we have to say about that in our "Detailed Summary."