In a corner of Maria Hernandez Park, a toddler teetered over to the new, gray thing lying on a patch of grass. With his tiny sneakers, he hopped on top — it didn’t move. With his little hands he reached for a cup — it didn’t move either. He stomped around and tried, unsuccessfully, to pick up a stack of plates. He giggled and waved over his mom, who indulged him for a minute or so before leading him back to the group.