Who invented the Gregorian calendar? Why do the 24 solar terms correspond to the Gregorian calendar?

The Gregorian calendar was invented by westerners, and the Gregorian calendar and the 24 solar terms in China all come from the law of the earth's revolution around the sun. Although the summary methods of the two companies are different, they both describe the same thing, which is definitely quite consistent.

The lunar calendar is based on the phases of the moon, so it is very intuitive to know what day it is today. However, China is an agricultural country, and farming is closely related to the sun. Twenty-four solar terms are calendars that reflect the solar cycle (that is, the earth goes around the sun once).