Have to agree with you concerning humans. The best thing that could happen for virtually every other species would be for us to be exterminated, not that I am advocating that! But I am talking about species introduced deliberately, or accidentally, by man, often in places where they would never have shown up under their own steam. We have done this countless times, with sometimes disastrous consequences. Usually because we either don't understand the implications of what we are doing, or because those involved frankly didn't give a damn. Nothing remotely natural about it. Where we have damaged an ecosystem by this recklessness, surely we ought to attempt to put the damage right.