Just realizing macOS X was released in 1999 which was based on Darwin which was an all new OS that replaced macOS classic. Since all Apple platforms are based on Darwin it makes sense to start the number in 1999.
https://en.wikipedia.org/wiki/MacOS_version_history#:~:text=macOS%20was%20first%20released%20in,10.0—shipped%20in%20March%202001.
https://en.wikipedia.org/wiki/MacOS_version_history#:~:text=macOS%20was%20first%20released%20in,10.0—shipped%20in%20March%202001.
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https://youtu.be/Pxdjhi53B8U?si=si2KAk5C6WVeJUh_