I agree with @Kitt. All inspiration is from external sources throughout our lives. They come from relationships, experiences, observation and reading. It is not the inspiration that counts, but what you create from that inspiration. Prompts can be varied from the ones you described, a theme like the anthologies or a picture as IOMFATS uses on his site. The creations from these prompts show a prodigious variety and diversity that is from the core of the writer, not the prompt.