A product manager is a broad generalist in early-stage startups, responsible for doing everything that's not engineering or design work. As the team grows, the role shifts to require specific expertise in various areas, and eventually becomes more specialized. A product manager connects user experience, technical requirements, and business requirements together, owning the "Job-to-be-Done" and having a vision for delivering a 10x product. The role involves both internal and external aspects, including communication, research, and fighting complexity, and is often misunderstood as being glamorous or easy to excel in.