Long ago, Egypt had different weather. So, you need to look at how things were different in the past. Warmer weather creates more rain clouds which then leads to a greener place, more trees. And by the way, even tropical places have winters. I was living in Vietnam for four years and they have winters. Now, their winter may not have snow and ice but it's winter. I would look at the ancient empires and look at the different things they did.
According to a history book written by H.G Wells in around 1920, he wrote that Christ was probably born around 4 B.C. In regards to which month Jesus was born. You could estimate based on whenever tax season was. So, you would have to correlate between the current calendar system and the calendars they used back then. So, you could estimate how long it might take to walk and travel to Bethlehem and later to Egypt. You can take the which ever numbers may be included in the Bible and in other books. I would look for history books which may document when the decree to kill all kids under the age of two because that order probably came within a few months after the birth of Christ. Some people believed Christ was born. They said a star appeared in the sky.
The star may have been the alignment of planets. So, another way to estimate the birth of Christ would be to study astrology or astronomy. Study the constellations and look at the patterns the planets are in and backdate the pattern of the alignment of planets back into time to estimate which month back then may have planetary alignments.
What do you mean by Da Vinci? Are you talking about certain things he wrote or are you talking about Dan Brown book called The Da Vinci Code? Who is Zeitguiest?
The modern version of Santa started mostly in the 1800s as an English word. But beyond that, Santa sort of looks like a big elf. So, the next question would be what is an elf. So, I'm saying there is more to it than just that. When I say Santa, I'm not talking about Saint Nick. I know the connection between Nick and Santa but Santa looks like a giant elf. And elves are part of a lore that has been around for thousands of years. Elves are just one of the many things out there on top of dwarfs and other things. I don't know if they're real or what. Some of these creatures may be imaginary, real, fake, alien, demonic, etc. Perhaps some demons portray themselves as elves. And that takes me back to the anagram of Satan and Santa. And so, what I am saying goes deeper than just the mere words I am saying. With almost everything I say, there is always more to it than just that.
By the way, English has been evolving for over a thousand years out of Germanic roots. And English is more modern than Hebrew. And English is a collection and a merging of different languages over the centuries or longer. English has so many borrowed words as it evolved from Old English to Middle English and then later on to a more modern version of English which started in like the 1700s or after, the last three centuries or less in some ways.
Since you mentioned Rome and Sol Invictus, I have to ask you what else you know about the Catholic church which came out of the Roman Empire. Catholicism is very Pagan. That is a giant can of worms which can fill many books full of many things.
You asked me if it's possible for Gentiles to appropriate Christian holidays to make them their own, and they do, but more importantly you will find similarities between different ancient world religions going back thousands of years. There is correlation between the Egyptian gods and the Greek gods for example. When you study ancient cults and religions, you will find different names and slight changes between what they might call different things or deities. Traditions, culture, customs, doctrines, beliefs, ideas, etc, are often built or at least influenced by ancient religions and what have you. They may have different words for what they call Noah's Ark and the world flood, and yet that story has been told for thousands of years from many cultures globally. It's very interesting to study the Tower of Babel and the different alleged gods they associate with that time period for example.
In regards to Easter, you should look at what the bunny represents. Before the birth of Christ, Babylon had Ishtar.
Halloween is very old.
Are Christmas trees in the Bible?
Are Disney movies pagan?
Does Santa look like an elf?
What is an elf?
Why do people think about Santa instead of Jesus on Christmas?
RE: Is Christmas a pagan celebration? (Part 2)