What inventions didn't attract people's attention at that time, but they were of great value later?

Winged glider, Leonardo da Vinci made a glider with flaps. This open-shell model is equipped with chairs and various equipment for pilots, but there is no helmet. The glider is designed to support the canvas wings with brackets, and the flight direction can be controlled by pulling the ropes at both ends. In addition, there is a big basket that can carry people, and it is equipped with wheels for lifting. Personal Comments: As an early work, this glider is similar to China's early manned kite. But the comfort has been greatly improved, which can be regarded as the combination of airship and glider, because it has a belly.