Why do you think a growing human population means mass extinction events for earths animals

if we wipe out an animals natural habitat, or introduce new wildlife the animals could die. This could cause a major problem in the areas ecosystem. That is what i know, and i think that major problems would happen, like to many of one species, which takes all the food from the other species, causing major problems, and even more animals to die.

the animal that would be cutest if scaled down to the size of a cat? elephant