On the first day of the traditional Chinese lunisolar calendar, the moon is a crescent, and on the fifteenth day, it is a full moon.
The specific month that is the first month of the calendar depends on the sun. The Winter and Summer solstices are determined by the longest and shortest duration of sunlight exposure in a day, and when the months and seasons are about to depart, leap months will be added. There are 7 leap months every 19 years. This ensures that the Spring Festival falls on the correct first month.
This is not because the Chinese like this complexity, but because of the limitations of the objective world. After all, the month means the rotation of the moon around the earth, while the year means the rotation of the earth around the sun, and the two are not multiples of 12 perfectly.
If you use the Chinese yin-yang(lunisolar) calendar, planting and fishing will be much easier. You look at the date sequence to know the shape of the moon and the sea tides, and look at the solar terms to determine whether to cultivate or harvest of different plants.