That's true, but it's not relevant as to why time is the same for everyone at your longitude.
The sun rises in the East, peaks at approximately noon, and sets in the West. Every point directly North or South of you experiences the sun peaking at the same moment in time. This also means that everyone in longitudes further East or further West of you experiences it at a different time, and people halfway around the world from you experience it 12-hours offset from when you do.
This is easily explained with a globe. But not so with a flat Earth.
Time is a social construct. The reason it’s the same time of day for others at your longitude is because people took a flat map and drew some lines.
That's true, but it's not relevant as to why time is the same for everyone at your longitude.
The sun rises in the East, peaks at approximately noon, and sets in the West. Every point directly North or South of you experiences the sun peaking at the same moment in time. This also means that everyone in longitudes further East or further West of you experiences it at a different time, and people halfway around the world from you experience it 12-hours offset from when you do.
This is easily explained with a globe. But not so with a flat Earth.