Hi Brianne,
How exciting to be planning your first trip to Walt Disney World with your five year old!
I suggest that you order the Walt Disney World planning DVD. This is free of charge, and your child can watch the DVD and look for things that he or she would like to do Walt Disney World.
As to attractions that are good for a five-year-old, it will depend a lot on your child. Your child may be tall enough to ride some of the somewhat more thrilling attractions, such as Big Thunder Mountain Railroad. If your child is interested in roller coasters like this, start with the more tame Barnstormer to see if thrills are the right way to go. There are many tamer rides in every park as well. For a five-year-old, I would say do not miss Peter Pan's Flight in Magic Kingdom, The Seas with Nemo & Friends in Epcot, Toy Story Midway Mania in Disney's Hollywood Studios, and Kilimanjaro Safaris in Disney's Animal Kingdom.
One of the great things about Walt Disney World is that nearly every restaurant is exceedingly child-friendly. If you are looking for a quick bite to eat, I like Sunshine Seasons in Epcot for fresh, delicious options. For table-service in a theme park, I like The Plaza Restaurant at Magic Kingdom for a great glass of iced tea and club sandwich.
I would love to help you with more ideas for your first trip with your five-year-old, Brianne; however, I am limited in the amount of space that I have to answer. Please do let me know if I can help you any more in planning this magical vacation!