The Ostrich farm and Baby Beach (the shallow water is great for kids) are other places you may want to check out while you are in Aruba. You may want to consider renting a car (most companies will also rent you vehicles with car seats if you request one) and driving around the island to visit these and other sites.

The Holiday Inn also has nightly shows (e.g. dancers) that would probably amuse your child. I would also take your child for a walk along the beach and visit the other hotels on the strip (for example, the Radisson has a number of exotic birds that your child would find interesting).

PS The Holiday Inn is in a good location and the pool (zero entry) and ocean (calm) are great for kids. All of the restaurants are also very child friendly and there are other children on the resort (i.e. people will not look at you funny if you bring your child to any of the restaurants). That being said, the planned kids activities and kid zone are geared towards older children. Furthermore, the Aruba and Bonnaire Towers of the resort only have showers in the bathrooms (i.e. no baths to wash your baby in).