The greatest hurdle in human interstellar travel is the "human" element itself. Had it not been for our desire to take ourselves to the stars, interstellar travel might have become feasible long ago. Humans are complex organisms with numerous demands, such as a constant supply of air, large quantities of food and water, as well as social interaction and medical care. Meeting these requirements necessitates considerable energy, infrastructure, and payload, adding weight and complexity to already limited rocket capacities. NASA’s five hazards of human spaceflight—radiation, gravity, isolation, distance from Earth, and closed hostile environments—become even more daunting in interstellar contexts. Disturbingly, proposed solutions, like "animated suspension" or "warp drives," remain in the realm of science fiction. The challenges posed by the "human factor" complicate interstellar missions extensively. While we could focus on purely robotic missions, to circumvent these issues, here it is essential to address the five significant challenges that remain salient for human interstellar travel.br Cosmic radiation poses significant challenges for interstellar flight, worsened by extended travel durations, high speeds, and vast distances. The absence of gravity also presents health risks for the crew and future generations. As humans venture farther from Earth, where our biology and psychology originated, adaptation to new environments becomes inevitable, albeit potentially detrimental. Initial changes may lead to chaotic or hostile behaviors, and managing such responses poses further concerns. The safety of reproduction in space remains uncertain, complicating human survival, given our physiological aversions to a zero-gravity environment. Additionally, maintaining harmony among crew members in confined spaces is challenging, as humans often exhibit negative emotions like anger and jealousy. With no known precedents for long-term cooperative behavior beyond a year, the psychological impacts on mission success are unpredictable. Interstellar crew dynamics will also raise civic and ethical questions regarding governance and cultural interactions, particularly as voyages might become autonomous and independent, necessitating discussions about leadership structures, language, and potential conflicts among diverse backgrounds.br In the distant future, if various challenges are addressed, humanity may have the opportunity to visit another star system. However, the reality could differ from our expectations, with humans potentially playing a subordinate role as observers, while advanced machines undertake the journey. Our once-held capabilities may have evolved into sophisticated technology. An alternative could involve transferring information rather than physical humans to the stars, as human biology and psychology are fragile.