These kind of questions are so open ended and are totally dependent on what the poster is wanting to do.
So, knowing that it depends on what you want to do, to do EVERYTHING, there is no way you can do it in less than a full day (assumes 9AM-9PM, 12 hour day). Everything assumes some wait in line based on average day. Shows assume arriving a few minutes early so you actually get decent seats, and taking time to file out after the show. The trails assume your not trying to qualify for the Olympics by running through them and not actually looking at an exhibit. I did not include the Boneyard, Wilderness Explorers, or Jungle Book/Rivers of Light
Safari with FP - 50 minutes
Everest with FP - 15 minutes
Kali with FP - 20 minutes
Dinosaur - 40 minutes
Primevil Whirl - 20 minutes
Triceretop Spin - 15 minutes
Nemo Show - 60 minutes
Lion King - 45 minutes
Flights of Wonder - 35 minutes
Tough to be a Bug - 25 minutes
Oasis - 15 minutes
Pangani Trail - 45 minutes
Jungle Trek - 30 minutes
Rafiki's Planet - 90 minutes
Tree of Life Awakenings - 15 minutes
Burudika - 10 minutes
Harambe Wildlife Parti - 20 minutes
Discovery Island Carnivale - 15 minutes
Other Random Entertainment - 15 minutes
3 random characters - 45 minutes
Lunch - 45 minutes
Dinner - 75 minutes
Two snack breaks - 20 minutes
Bathroom Breaks - 20 minutes
Shopping - 30 minutes
That's 815 minutes, which equates to 13 hours and 35 minutes. And that is assuming no Rivers of Light. Families with small children could also add time with the Boneyard, Wilderness Explorers, increased Characters M&Gs, and more frequent breaks.
Animal Kingdom is not a half day park (nor is Hollywood Studios when you put the math to it).