Question

ve
What would happen; it there were no
animals in the world?​

Answer 1

If there were no animals in the world, we humans would not have existed too. (as we too are animals)

I think you mean to say - What would have happened if there were no  animals (except humans) in the world?​

Well, then also I think, we would have not existed. We evolved from different animals and if that animals did not exist, we would not have existed.

Even if somehow, we existed, our population would have been much less. Most of humans eat other animals. So, if animals did not exist, all the humans would have been dependent on plants, which alone would have not been sufficient to 7 billion people. Moreover, in the process of growing more and more crops, we would have not developed much.

Also, the in-existence of animals would have been a great loss to the plants. Many animals (like bees, bats, etc.) pollinate and thus, help in reproducing plants. So, without them, plants would have not grew much in numbers.

A lot more would have happened if animals didn't exist. But luckily, whom-we-call "animals" exist and so do humans, which is why I am able to answer you to the question - What would happen if there were no  animals in the world?

(Sorry for my grammatical mistakes.)