Large animals that live long lives don't have any real information in their DNA. Essentially every species runs it's own genetic algorithm.
Large animals have a generational gap of, let's say 5-10 years, and have numbers in the tens of thousands. Bacterial generational gaps measure in minutes to hours, and their numbers are so large there are no confident approximations. Unsuccessful bacteria species number in the thousands of trillions. One can only imagine what the numbers are for successful species.
This means that the genetic algorithm running a pathetitc bacterial species has a clock speed something like 100 terahertz. It does 100 trillion calculations per second. The genetic algorithm that runs "on" the human race has a clock speed of around 5 calculations per second. For most animal and plant species, the speed would be significantly less than 1Hz. Guess which of these two makes the discoveries ... (the theory being that viruses, on rare occasions, transplant DNA "discoveries" from bacteria into other species, so while humans do evolve, they rarely, if ever, successfully mutate. Rather we are the product of natural genetic manipulation by viruses and natural selection. The same applies for plants and other animals)
The reason large animals survive at all is that their biomass just does not register on the "success" charts for bacteria. Killing every single plant and animal on the planet and fully converting all that mass into new bacterial biomass would not represent 0.01% change in population size for bacteria. That is the only reason why animals survive : we're simply neither a threat, nor a worthwhile target.