What if there was no sun and moon?

Our perception of reality is limitless. The illusion of time restricts us by bringing us back to an endless cycle. Just like how the sun and moon rise every day. How the weeks come and go constantly. There’s a start and end to their patterns/cycles, or so we are led to believe. A sunrise to you is sunset to another person viewing it at a different location. But let’s entertain ourselves with a little thought experiment: what if the sun and moon were artificial objects instead of natural? What if the sun and moon are smaller than we were taught in school? What if they were put into place to establish the concept of time for us? Without the sun and moon to enforce time, would we still have a calendar and clock in this reality?