You can decorate your kid’s room based on the jungle theme. Ask your child and take his opinion about what he is interested in. you can paint the walls in such a way that it represents a jungle. Use different shades of green. You can use stencils of leaves to give it a more realistic look.
You can buy a comforter set with a jungle theme. You can get a quilt made by someone based on the jungle theme. You can make a green quilt. Attach a mosquito net on the bed to give it a jungle feel. If your kid is old enough, you can purchase some plants and keep them in the room. Try buying Philodendrons which are hardy and inexpensive.
Accentuate the jungle theme by placing stuffed animals like tigers, monkeys, cheetahs and hippos. Place them all around the room. Use appropriate lighting for the room, like Christmas lights etc.