The problem with most evolution theories based on randomness is that they largely depend on mutation. The same people who insist that science should be based on objective observation fail to admit that the overwhelming majority of mutations make a creature less adaptable. I can see certain instances where, perhaps, a genetic predisposition to certain coloration or patterns may make an animal a better hunter or a more difficult prey, but most random mutations adversely impact the health of the organism.
Well, those words are key, aren’t they? all it takes is a “small minority” for evolution to work.
We’ve seen species disappear. We’ve seen species that were thought to be extinct re-emerge in small numbers. We’ve seen plants and animals migrate (via hobbyists/scientists/shipping) to new regions of the world where sometimes they thrive.
New lifeforms springing up, not so much.