That light travels from the Sun to us enables us to see it. But it also enables us to track its path. Its the light arriving here that enables us to infer so much of what we know about the universe.
Simple direct observations show that the Sun rises in the east and sets in the west and that there is a difference in the height of the midday Sun between mid-summer and mid-winter. This information will (later) help with the explanation of the cause of the seasons. For now, its useful for accounting for day and night.