For what purpose did people combine the stars into a constellation?

The ancient people did not have any instruments for observing the time, no calendars, no compass. The Sun and the stars were the only guideline for determining the time of day, the change of seasons, the direction of movement in the steppe, in the forest or at sea. Since there are a huge number of small luminaries, and the appearance of the starry sky changes depending on the time of year or day, from geographical latitude, people chose the brightest stars, combining them in groups, mentally connecting them with segments. Then, to make it easier to remember, they gave them names and came up with legends. Each nation had its own names and legends. At present, the ancient Greek names of the constellations are generally accepted in astronomy.