Leonardo da Vinci's 1489 “aerial screw” is commonly recognized as an early helicopter concept.
The drawing shows a large helical rotor made from reeds, linen, and wire, supported by a circular platform. Leonardo reasoned that the screw could rise if its rotating surface pushed against the air, much as a screw advances through water. The machine was intended to be powered by people turning internal mechanisms.
The design was never built by Leonardo and could not have lifted itself with the materials and human power available in the Renaissance. Its rotor also lacks the aerodynamic efficiency and control systems of a modern helicopter.
The aerial screw is therefore best described as a conceptual ancestor, not the first working helicopter. Modern helicopters became practical only after lightweight engines, improved rotor theory, and reliable controls were developed.