Originally, lighthouses would have an open fire at the top of their tower, fueled by wood or coal.
For example: the first known lighthouse. the Pharos of Alexandria
(305 BC - 1303 AD, illustrated here in 1572)
Sometimes religious hermits or monasteries be paid a small fee to light fires at the tops of hills or natural rock towers to serve as guides to shipping.
Of course, an open fire consumes a lot of fuel, and may or may not produce sufficient light to be seen far at sea, so as shipping increased, more effective forms of lighthouse lamps were experimented with.
Candles are easier to handle than open fires, but don't cast a large amount of light, but what if you places silvered mirrors behind the candle to reflect the ambient light all in one direction? When Boston Harbor Lighthouse was lit in 1716, it used tallow candles for illumination.
When the Argand lamp, an oil lamp creating as much light as 7 candles, was invented in 1780, they were integrated into parabolic reflectors to increase light in lighthouses while reducing fuel consumption.
Multiple lamps and reflectors would be placed in the tower.
in 1812, the "Lewis Patent Reflector" was purchased by Pleasenton, then in charge of the Lighthouses of United States, and was installed in all US lighthouses. This apparatus consisted of multiple Argand lamps + reflectors that burned whale-oil mounted on a frame Glass magnifying lenses were also placed in front of the lamp. A similar (but higher quality) arrangement was used in European lighthouses.
This was the first style of lighthouse lamp that could be rotated.
So, to put it simply: while lighthouses were first built starting 2000 years ago, there was not the technology to create rotating lenses until about 1800.
Of course, the primary reason to make a lighthouse lamp spin is to make it flash. The reason to have a flashing light is so that different lights can have different flash patterns (called 'Characteristics') so that you are able to tell them apart. Rotating (and thus flashing) lights were only installed in lighthouses that were close enough to another lighthouse that it became necessary to have a way to tell them apart at night. Prior to 1800, there just weren't a lot of lighthouses around in general.
As for the Lewis Patent Reflector, they were very low quality. After the introduction of the extremely successful Fresnel Lens in 1823, European lighthouses quickly switched to the new technology. America dragged its feet on replacing its Lewis Reflectors for a variety of reasons until ship captains complained so heavily about the shitty quality of the light of American lighthouses that the US was forced to switch over to Fresnels as well.
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