The trebuchet was used to break into castles and forts. If they weren’t invented, there would probably be more castles and forts still standing today.
Distilled Spirits were an innovation in alcoholic beverages. If they didn’t exist there wouldn’t be booze today.
The vertical windmill was used to turn grindstones and generate power later on. If they didn’t exist, all of this world’s power would be from power plants and hydroelectric dams.
The rudder allowed steering for ships. If it didn’t exist, ships and planes wouldn’t work.
Stuff That Jack Built 