There is simply no way for any unguided, unintelligent account of the unfolding of life to avoid the bane of helpful degradative mutations.
Scientists debate whether ctenophores are the earliest animals to appear in the Cambrian explosion. If so, they arrived with multiple tissues, a nervous system, and a digestive system.
Genetics is now a subset of epigenetics, in which multiple dynamic molecules play key roles in homeostasis.
This odious stuff never ends.