What do the animals in the animal kingdom have in common?

they main thing the have in common is they all are living things, and have a heart, lungs and a brain.

Not every animal has a heart, lungs and a brain. Only land animals have lungs, and jellyfish and sponges don´t have a heart or brain, not to speak of single-celled animals. The universal thing about animals is the fact they´re made out of cells without a cell wall or chloroplasts like plants have.