I will start by noting that several essential gods of different ancient pantheons can be identified as being the same or equivalent deities, with different names (and small variations in their stories).
Some authors identified the supreme god Ahura Mazda with Zeus.
The Egyptian supreme god Amun-Ra was the same as Zeus or Jupiter, also called Zeus Ammon or Jupiter Ammon.
Sometimes there was more than just a “triad” of important gods, such as the Ennead or Great Ennead, a group of nine deities in Egyptian mythology and ancient Egyptian religion, worshipped at the city of Heliopolis.
The Ennead included the sun god Atum; his children Shu and Tefnut; their children Geb and Nut; and their children Osiris, Isis, Set, and Nephthys. The Ennead sometimes included Horus, the son of Osiris and Isis.
Atum was equated with the sun god Ra. In the New Kingdom, when the god Amun rose to prominence he was merged with Ra as Amun-Ra.
In the ancient Canaanite and Phoenician religions, Baal is the equivalent of Zeus, and the god of the sea Yam is the equivalent of Poseidon or Neptune. The god Mot is identified with Hades or Pluto.
The Babylonian king of the gods Marduk was associated with Zeus by the ancient Greeks, and associated with Jupiter by the Romans. There is an ancient Hittite and Hurrian group of texts known as The Song of Kumarbi, “Song of Emergence” or Kingship in Heaven. Scholars have pointed out the similarities between the Hurrian myth and the story from Greek mythology of Uranus, Cronus, and Zeus.
In Hinduism the chief god Indra has many characteristics in common with Zeus.
It is possible to notice that several ancient religions or cultures were connected and had a common origin. One could observe or suggest that these ancient religions and the related ancient stories and mythologies had their origin in the ancient Near East, West Asia and the (eastern) Mediterranean, plausibly based on some events that were rooted in history. A second related source of origin pertains to ancient India and the ancient Hindu religion, since the ancient Indians had many historical interactions with the ancient Persians in terms of cultural exchanges and political influence (particularly during the Achaemenid empire), language, religion, spirituality, etc. The ancient practices, beliefs, ideas and religions spread to the entire Mediterranean region and to the south of Europe, to Greece and Italy. It is plausible that these ancient religions, stories and practices also spread (with some modifications) to the north and to other parts of Europe through a process of gradual cultural diffusion, influencing the formation of ancient Germanic and Norse religion(s) and mythology.
In light of my readings and analysis, it can be said that whether polytheistic or not, religions and cultures are interconnected in one way or another. The ancient allegorical stories of gods and deities that were constructed, embellished and changed with time could be explained reasonably by philosophical doctrines similar to Euhemerism, where these diverse embroidered stories are considered to be rooted in history. A very plausible and a realistic explanation of the origins of ancient religions is that most of them (in the ancient world and in the Mediterranean region and the Near East, and beyond), started mainly with a man who lived in ancient times, most likely about two millennia before the beginning of the Common or Christian era. This man did great and important things, accomplished great deeds, and brought about new innovative teachings and ideas for his time. This man left a lasting impression on those who saw or knew him. When he died he was revered, his life and actions being interpreted in different ways and directions. There were people who revered him a lot, divinized and deified him or started worshipping him.
This man was later called Amun Ra by the Egyptians. He was called Baal by the Canaanites and the Phoenicians, Zeus by the ancient Greeks, and Jupiter by the Romans. He was very likely the same deity as the supreme god Indra of the Hindus (since Zeus and Indra had many similar characteristics), Ahura Mazda of the ancient Persians, as well as other supreme gods in the ancient world.
Regarded as the head of a pantheon (or several related and connected pantheons, with small or minor differences between them), and as the father and ruler of the gods, he, his family and the other related deities had their stories transmitted, retransmitted, interpreted, reinterpreted, and modified over the years and centuries. Supernatural, symbolic and metaphorical elements were added to the stories of the gods with the passing of time. Each generation or group of people interpreted these ancient stories according to their understanding and their cultural and physical environment.
Did this man or person want to be deified or worshipped? He likely wanted to live his life and “do what was needed”, he knew that he was doing important things and that he was going to be remembered, but the deification or worship and the subsequent rituals and religious practices were mostly the result of the interpretations and choices of those who knew him, liked him, and/or followed him.
A thing that has been somewhat forgotten in the last two centuries is that many authors of the past, from the ancient Babylonian author Berosus to Isaac Newton and others, stated or were of the opinion that Zeus or Jupiter was the same person as one of the earliest and most important patriarchs in the Bible, his story having been modified to comply with biblical monotheism.
Another man came and lived about two millennia ago. He did important things, brought about new innovative teachings and concepts of morality for his time, and left a big impression on those who knew him and on his followers. He was subsequently revered, deified and worshipped by his followers, his story being interpreted and explained in various and different ways and directions, with allegorical and supernatural elements added to it. This man is mostly known by the name of Jesus.
About three centuries after his passing, the religion with Jesus at its head gradually replaced the religion having Zeus or Jupiter at its head.
In the same way that the one known as Zeus or Jupiter was mentioned as a very important patriarch or prophet in the monotheistic Bible, Jesus was later mentioned as a very important prophet in the strictly monotheistic Quran.
During the last century and the last few decades, a progressive change in mentalities and a regain of interest in ancient philosophies, ancient cultures, and ancient religions took place. Taking into account the evolution of ideas and the progress and advances in science during the last centuries and decades, there is a possibility that a new transmutation of values is gradually taking place, related to some sort of periodical or cyclical return of historical events, being the inverse of what happened at the start of Christianity two millennia ago. In any case, one will have to wait, see and look at the unfolding of future events.