On my recent vacation we went to Disney World for a few days. At our "resort" they had bicycle rentals, but you could only ride them around the resort itself. And the same is true of other resorts. The parks and resorts are spread out over a large area, but not so far you couldn't bike between them - if there were ways to do so, but even BikeOrlando says
Biking between resorts is not recommended as there is a lot of traffic on the main arteries.
I would have strongly considered getting a Surrey and throwing the family on it to go to various parks, if a grade separated trail network connected everything. (Then I could buy a Monte Cristo without feeling guilty about my blood sugar).
I'm not going to figure out what that would look like, but at least one person took a crack at it (I'd add a trail along Osceola Parkway). It would be even better if one could do Surrey-share and pay by the day, picking up bikes as needed and leaving them when they don't. It would be an added amenity in itself (people would probably like to run, walk and bike the paths just for fun) create a healthier, cleaner park and it might even reduce their transportation costs if it lets them run fewer buses.
On the last day I had to pick up a rental car from their on-site rental car facility. My app recommended taking the Monorail to the Polynesian and then walking the 1.3 miles to the Car Care Center, which seemed reasonable to me. The route unfortunately took me along a road with no sidewalks (pretty common) but I was OK with it. Traffic was backed up and slow. Still, Disney Security picked me up and gave me a ride because it was just too dangerous to walk along the road. If a trail system can't be built, maybe some sidewalks?