Why there is 28 days in feb only why others months not have only 28 days?

In my opinon Feb has 28 days because the first month (Jan) started with a large amout of days (31).They could not devide the rest so the they took the first month of less days(Feb) and instead of making it 30 the made the first month of less days(Feb) 28 or as we say on a leap year 29