It’s called a cascade extinction event. With each endangered species their ecosystem is affected, leading to more becoming endangered. Eventually a threshold will be passed where human intervention won’t be enough to save them from extinction.
Yes and no, the humans doing the "saving" and the ones doing the "killing" are different groups. So it’s still technically a save but only as far as different humans have different interests. The culpability is still as a whole on us as a species.