Hi Bess,
Disney's Animal Kingdom Villas - Jambo House is a beautiful resort. Not only are the animals amazing, but the interior of the resort is beautiful as well. There is so much to do for young children at this resort, I would say that you could spend an entire day and not be bored at all. Or, if you prefer, you can take in the activities at the resort a little bit at a time - maybe one each day - and then have slightly shorter days at theme parks. This might be a good idea since your children are so young that a shorter day in the theme parks might be nice for them.
When we stayed at Disney's Animal Kingdom Villas with our daughter, she really enjoyed cookie decorating at Boma. She also loved simply watching the animals, either from our balcony or from the public spaces like Arusha Rock. She also enjoys the pool activities at all of the Walt Disney World resorts, including Disney's Animal Kingdom Villas. These can include pool parties and games. Recent offerings of activities at Disney's Animal Kingdom Villas include African face painting, making rubbings of medallions in the amazing lobby, and a Drum Cafe where you can learn to play African drums. Also, check out the
recreation offerings at Disney's Animal Kingdom Villas - Jambo House online. This site includes information about the campfire, arcade, and playground, among others. Please do note that all activities are subject to change.
When you check in to the resort, be sure to look for the activity guide that you will be given. This will list all of the activities happening at Disney's Animal Kingdom Villas during your stay.
I hope that this information is helpful for you, Bess! Please do not hesitate to ask if you have any further questions.