I'll repeat my question: Which is the first day of week/creation?
The question can not be answered without context since different cultures has the day at different days.
I think the whole things is based in astronomy.
Those who looked and studied the sky noticed a certain pattern,they noticed that something repeats every 7 seven days so a week was made to have 7 days.They also noticed something else repeats every 12 months and hence a year was made to be 12 months.
What is important is that there are seven days in a week.What day exactly is the first day is just a matter of convention.
The bible for example says GOD created the world in six days and rested on the seventh and called the seventh day "sabbath". People do not rest at the beginning of work,they rest at the end of work so from the bible's perspective,it makes sense for sunday,a day after sabbath to be the first day and it makes sense for cultures with christian traditions to have sunday as the first day.
Just to be clean,above is what the bible says,lets not debate if GOD exists or if he created the world or anything like that.
Different cultures that grew separate from the bible would have the same seven days but the first day would be on a different day.
In swahili for example, as i have said many times, the language has the first day fixed at saturday. Why is that? I do not know but i suspect it has to do with islam or arabic culture since a lot of time keeping in swahili language is borrowed from arabic language.
If you ask a swahili speaker,"what day of the week is the first day?",the one would be "saturday" because it does not make sense to say "day two" as the first day.
I understand the chinese celebrate new year is February,If you ask a chinese, "what month is the first month of the year" and they would probably say "February" and that would be correct based on their calender.
Do we have anybody from different cultures? Or who people languages that specify days by numbers?This is the easiest way of knowing when that culture thinks when is the first day.