The only problem with this take is the natural man and his works are not God pleasing
I tried to come up with a better word than “natural”, because of its unfortunate connotations. But in this situation, it is accurate. No need for a “natural” man living in “the state of nature”.
The temperate and higher latitudes have seasonal weather that has affected agriculture since before there were written records, to this very day.
When the harvests came in, everyone feasted both because they could, and because they knew that winter was on the way. Then, at the very bottom of winter, there was intense interest for “when the sun is coming back”, which was also a feast. And finally, when the new crops came out in spring, their was a third celebration, because stores were getting slim from the previous harvest.
This is why, around the world, the equivalent of harvest, then just after winter solstice when the sun could be seen returning, and just after spring solstice are almost universal holidays. Other holidays are less important because they are often commemorative.
Since, in the early Christian church, they didn’t have a real fix on the genuine commemorative days, it was very easy to ascribe these days to existing “natural” days of that character.