The Creator actually created degenerating creatures?
Not necessarily. The entire structure of the DNA (including all kinds of matching, fixing and correcting mechanisms) is anti-mutation oriented. Everything is focussed on preventing mutations. The fact that mutations still happen comes forth out of mutagenetic substances and/or by radioactive radiation, but not by genetic mechanisms that cause mutations on purpose. On the contrary, there are many genetic mechanisms that prevent and even fix mutations. When the circumstances of life on earth would have been like this that radiation and all did not exist, then there would never have been degeneration. The frequency of mutations does not have to have been the same as it is today. There could have been times when it was much more, or just much less.