When our son was 2 he loved Animal Kingdom.
I would suggest you head straight for the safari. When you exit the safari, take the gorilla trail. When you leave the gorilla trail, go to Rafiki's Planet Watch. We've been able to get up close and personal with a two foot long alligator and a HUGE python. The castmembers let us touch the animals and gave us hand sanitizer afterwards. There are usually several characters at Planet Watch. Outside, there are some goats and sheep that can be petted and combed. A hand washing station is nearby.
By this time, you will probably be ready for lunch. I would suggest you go back towards the Tree of Life and stop at Pizzafari or Flame Tree BBQ.
Check out a park schedule. If Legend of the Lion King is scheduled in the next hour, head to Camp Minnie Mickey. There you will find character trails. Usually, you can see Goofy, Mickey, Minnie and Donald. Sometimes the characters from Brother Bear are there too. Go see Legend of the Lion King. There is constant movement and songs so your little one should be enthused with it all.
The afternoon parade is usually at 4:00 p.m. You may or may not want to check it out. It's bright and colorful and should hold your 20 month olds attention.
Next, head over to Dinoland. Ride the Triceratops Spin. (This land is skippable if you are not riding Dinosaur.) Check your park schedule. You could get in to see Nemo the Musical. We haven't seen it yet but the reviews are great.
From there, head over to Asia via the walkway from Nemo the Musical. Go thorugh the Maharajah (spelling?) Jungle Trek. There are tigers, hippos, deer and an aviary.
After that, you can take your time and explore all the animal trails if you'd like. I would really hate to see you guys skip the Animal Kingdom because you think there's nothing a small child to enjoy. The Animal Kingdom is definitely not just a zoo!
Hope this helps with your decision making process, Lisa