6. If humans descended from monkeys, why are there still monkeys?
This surprisingly common argument reflects several levels of ignorance about evolution. The first mistake is that evolution does not teach that humans descended from monkeys; it states that both have a common ancestor.
The deeper error is that this objection is tantamount to asking, "If children descended from adults, why are there still adults?" New species evolve by splintering off from established ones, when populations of organisms become isolated from the main branch of their family and acquire sufficient differences to remain forever distinct. The parent species may survive indefinitely thereafter, or it may become extinct.
I personally don't consider this to be a mistake (although you are correct in stating that there is a point there that Ferndina does not understand). It is true that modern monkeys and humans descend from a common ancestor, but I'm fairly sure that our last common ancestor, if it could be examined by people today, would also be classified as a monkey (and our last common ancestor with apes, an ape). I thus have no difficulty in stating that humans descended from monkeys and apes.