Original sentence: It depicts a secular humanistic future in which man has overcome sickness, racism, poverty, intolerance, and warfare on Earth; the central characters explore the galaxy, finding new worlds and meeting new civilizations, while helping to spread peace and understanding
Edited sentence: It depicts an optimistic future in which humankind has overcome sickness, racism, poverty, intolerance, and warfare on Earth; the central characters explore the galaxy, finding new worlds and meeting new civilizations, while helping to spread peace and understanding