Why is the January 1st at this time of a year?

Question

Why is the January 1st at this time of a year
chosen as the beginning of the year rather than any other day during the one-year cycle, e.g. the winter solstice?

Answer 1

Like I said in the other answer, this was a convention of the gregorian calendar.
Gregory was a mideaval Pope, and the mideaval folks were all about having things done in an orderly way. So it would have made sense to him to have the year begin on the first day of a month rather than some odd day in the middle of the month such as winter solstice. Moreover, the Gregorian calendar was adopted to correct slight inaccuracies of the Julian calendar, so those who designed it would have been acutely aware that winter solstice does not always happen at exactly the same time. It can vary by several hours, even occurring sometimes on Dec 21 and sometimes on Dec 22. So they would have wanted a nice fixed date to begin the new year. The first day of January would have been the best candidate, becuase they believed that Jesus was born near the end of December. In the same way that all years were dated from the year after Jesus was believed to have been born (eg, he was believed to have been born in the year 0 AD/BC so he would have been 1 year old in 1 AD, etc), so also each year begins in the month after Jesus was believed to have been born.
This is all speculation on my part, but it is based on how the churchmen at that time reasoned. They would not have used any kind of scientific or astronomical reasoning to choose that date, because the church at that time was very distrustful of science and astronomy, even prosecuting early scientists as heretics. Remmeber, they believed that the earth was flat and was orbited by the sun because the bible said so.

Answer 2

it is the first day of a new year where you can make a new start and forget all last years problems and look forward to the future