We need to save wildlife because all animals and plants rely on one another for their survival. For example, certain flowering plants rely on hummingbirds to pollinate them or else the plant dies and/or can't reproduce. If we do not save them, then thay will become extinct. When one thing becomes extinct, it impacts something else and that goes extinxt or becomes overpopulated and the pattern continues like that all the way up the food chain - which even impacts us sooner or later.
Hope this helps:)