Holy day is the origin of the word holiday, so when someone says “happy holidays,' they are saying, whether or not they realize it, happy holy days.
Many parts of the world have had celebrations at this time of the year back into ancient times. It probably started as a celebration of the winter solstice, when it was confirmed that the rising sun was now rising farther north every day and not farther south, and that the days were now getting longer. People would set up stone circles. You start out with an unmovable center stone, then every day at sunrise and sunset one person would move a stone on the edge of a circle to the point where it is rising as seen by another person at the unmovable stone in the center, and again at sunset. When the sun has reached it's furthest south point of rising and setting you leave those stones there, then do the same in the spring and find the northern most rising and setting positions. You now have the beginnings of a useful stone circle, and a calendar, and intermediate stones may be put in place. Bisecting the solstice angles give you north/south and east/west lines, and you put stones in their appropriate positions. The Sun rises and sets over the east/west stones at the time of the equinoxes when day and night are equal length, and a line between all three stones (east, west and center) is a straight line. Over time, the village learns at what position relative to the stones it is good to plant different crops, and when to harvest. (And millennia later fake Druids will show up at important times.) So, when the sun begins to move north again, we call it the winter solstice and the beginning of winter, and it's time to celebrate. (People were smart back then.)
Information on Christmas time in the past can be found here:
https://www.history.com/topics/christmas/history-of-christmas
If it seems to you that Christmas is a mixture of the religious and secular, you're right. Rome had a holiday period just before the solstice honoring the God of agriculture Saturn wherein businesses and schools were closed, slaves were temporarily freed, (America did not invent slavery), and people visited and indulged in food and drink. A period when normal life is somewhat suspended and one may reflect on life, the universe and everything, much like our present holiday period.
It's not stated in the Bible just what time of year Christ was born, but there's a good chance that it was the Spring since it's thought that that's when the Romans did their census. Since the time of year is an unknown, we might as well celebrate it at Christmas, but don't take that as a diminishing of the importance of the birth of Christ. He said he was the connection between man and God, and I believe that was correct.
There seems to be an effort by our elites to remove the religious aspects of Christmas, exactly why is unclear. Possibly it's due to their own atheism, but there is also the fact that a retail store does not want to alienate any of the customers. Many of the elites just don't like that spiritual beliefs make people harder to control, but they can't eradicate it. Even in the absence of formal religion people have remarkable experiences pointing to greater things; miraculous survivals, meetings with angels, etc.
A little more Christmas astronomy. The orbit of the Earth is somewhat elliptical, and the Earth's closest approach to the Sun, or perihelion, happens in January, so the Earth is moving at it's fastest at this time, so the sunrise and sunset happen a little later in the day than they would otherwise. This has the effect of making the time of earliest sunset come roughly a couple of weeks before the shortest day, at the solstice, and the time of latest sunrise similarly later, in January.
The Earth being closest to the Sun in January means that the difference in temperature between winter and summer is less than it would be if the distance was closest in the summer, and you might think that the southern hemisphere would have a much larger differential. That it's not the case is because there is a great deal more ocean area in the southern hemisphere than in the northern.
The Earth of course rotates on it's axis through the poles, but think of a spinning top that begins to wobble. The Earth does the same thing, and it takes twenty six thousand years to complete such an oscillation. As it oscillates the point in the orbit where the solstices and equinoxes occur move, so in thirteen thousand years the Earth will be closest to the Sun when it's summer time in the northern hemisphere, as it was thirteen thousand years ago. Then the winter versus summer differential will be larger in the northern hemisphere than it is today, and smaller in the southern. Thirteen thousand years ago the Sahara was a wet place, so maybe it will be again when the Earth's axis of rotations has gone through another half cycle; after all this must play hob with the monsoons. This is all very convenient for our would be overlords, because it means the climate will change big time no matter what we do, and they can say we need to enslave all mankind.
I'm not a climate scientist, and I don't play one on TV, so that's my little non-professional input. That climate science is being used by the powerful to amass more power is a sin. Real climate scientists have had their reputations attacked for promoting non-approved facts and ideas.
"A little smile, a word of cheer, A bit of love from someone near, A little gift from one held dear, Best wishes for the coming year. These make a merry christmas!" ~ John Greenleaf Whittier
So forget all the political stuff for a while and remember family and friends are more important, enjoy Christmas and don't be too upset if someone says Happy Holiday, remember they are really saying happy holy days, though they may not realize it. Take your mind out of the eveyday humdrums and recharge your emotional batteries, and don't let any woke relatives bother you. And if little Johnny wants a toy gun for Christmas it's okay – it will help ease him into manhood.
"Christmas waves a magic wand over this world, and behold, everything is softer and more beautiful." ~ Norman Vincent Peale
Not quite the same as my usual essays, but hey, it's my choice, and I've always found Astronomy interesting.
Stay Brave, Stay Free
... and happy holy days to you ! 🌠
Merry Christmas