> Any alien observing the planet over the last 4 billion years would recognize us as an anomaly.

An anomaly, sure, but they could very well view us as a natural anomaly. We're talking about fiction now and there's plenty of fiction that runs along these lines (aliens view humans as humans view other animals).

> Polluted cities, sucking in value from all around, at the cost of countless species have often been compared to cancer.

Not a great sign when your worldview is exactly the same as the villain in The Matrix...