No, humans cannot fly without the aid of machines or devices. Gravity is a fundamental force that attracts objects with mass toward each other. It is the force responsible for keeping our feet on the ground and objects from floating away.
While humans have developed various means of flying, such as airplanes, helicopters, and other aircraft, these methods rely on mechanical systems, engines, and aerodynamic principles to counteract gravity and achieve flight.
In the realm of human biology and physiology, our bodies are not designed for sustained flight. Humans lack the necessary anatomical features, such as wings or lightweight and efficient muscles, to generate the lift required for unassisted flight.
However, it's worth noting that humans have developed activities like skydiving, paragliding, and BASE jumping, which provide the sensation of flying. These activities involve using specialized equipment and harnessing natural forces like air resistance or wind currents to glide or descend through the air, but they still do not involve sustained, unaided flight.
In summary, while humans have harnessed the power of flight through technology and machinery, unassisted human flight without the aid of machines or devices is not possible due to our biological limitations and the fundamental force of gravity.