You could argue that insects dominate the animal kingdom. It isn't their fault that they're only little. They've been around for hundreds of times longer than us and there are millions of species and insects are found in almost every habitat bar deep oceans. As for adapting to conditions and predicting consequences, let's see how we're getting on after another hundred years of global warming.

Darwin worked on the natural selection of heritable traits, not survival decisions. The only sense in which his work was "incomplete" is that he didn't have access to information about genes and genetic codes carried on DNA.