1, "There is no pure gold, no one is perfect" means: there is no pure gold. Metaphor: Nothing is perfect. It is also a metaphor that you can't ask a person to be free from faults and mistakes.
2. "Natural people have their own strengths" means that everyone is born with some special talents and skills. This sentence emphasizes that everyone has unique advantages and strengths, and should give full play to their own advantages instead of pursuing perfection excessively.