No skeptic says a mundane explanation is unknown. That assertion makes zero sense. No skeptic rules out extraordinary explanations, they simply find insufficient justification to resort to them - as is the rational approach to analysis. So that assertion makes no sense. Those assertions you made are a] strawmen (since no skeptic says what you claim), and b] non-sensical, for the reasons above. They are also, by the way, ad homs, in that they bypass attacking the skeptical argument and instead seek to weaken the argument by attacking the skeptical arguer. That is not a rational approach.