Hi there, Trisha!
Every hotel at the Walt Disney World Resort offers a shop that sells basic snacks, foodstuffs, and sundries.
Disney's Port Orleans Riverside features Fulton's General Store, open daily from 8:00 AM - 11:00 PM, hours subject to change. This store does have a small selection of baby food as well. Prices are comparable to your favorite convenience store.
You are also welcome to use one of the local grocery delivery services to bring items right to your hotel. Garden Grocer is a real favorite, and their ratings have always been excellent.
Finally, you can opt to mail yourself items in advance. This might be good for your baby food, especially, since there is no guarantee that you'll be able to find your little one's preferred brand / flavor.
Simply address the package to yourself in care of your Resort hotel. You are welcome to use any mail carrier. Make sure to include your date of arrival and your confirmation number in the address. Your package will be held for your arrival.
Have a wonderful trip!
See you later, celebrator,
-Deborah B.