My mild problem with evolution

In the beginning there was creationism.  Then knowledge expanded and science proved itself useful and people realized that many of their original ideas were wrong.  Evolution was a fine advance in the theory of everything.  Since then though progress on that theory has stopped and people have replaced it with endless waves of confirmation bias.

Both creationism and evolution are unprovable, after all, it’s not like we can recreate either one in a lab.  Any evidence that comes up can be cherry picked and rationalized, I can come up with several plausible theories on why birds have feathers, why women are (supposedly) more monogamous than men, why we have genders, etc. But it seems like Darwin came up with the theory of evolution lo those many years ago, and everyone stopped looking for theories on the origin of the species, and just set out to defend it against creationism, and never put any effort into coming up with something better. It’s as if someone discovered that it was easier to haul crops into town on a wagon, and then committed himself to the wagon, and no one ever thought of the truck.

Why hasn’t there been anything new?