The sun rises to its highest point and then sets, so it makes sense to split time in two parts. Think about ancient sun dials. 12 and 6 were common for other units of measure because of the way they divide evenly. 360 became a common division of angles because of how all the important angles (90, 45) were whole numbers with that division. 365 was the total number of days  observed between the shortest and longest days, and 24 hour days were the set of divisions that won out. Even as later culture learned a year was really 365.24, the 24 division was kept, but with leap years/seconds added in.

The current clock/calendar makes a lot of sense when you view it in terms of units that divide evenly into partitions of whole numbers.