The concept of Satan is one that evolved over millennia and had many various influences. But we can start with those verses you pointed out.
Isaiah 14:12. It is true that this is where the name of Lucifer comes from. It was in the Latin Vulgate the we see the term; however, Lucifer, as we think of the term today, is incorrect. The term begins as the O Shining One (or Daystar), which goes to Morning Star (which is still how Catholic translations and commentaries view it), and finally Lucifer.
But to understand the text, we need to ignore the later names, and go back to the more accurate translation of Daystar. We also have to be familiar with the Ras-Shamra (or Ugaritic) poems, as there are a number of points of connection between this section in Isaiah, and those poems. Just a note on Ugaritic literature as a whole. It is exceptionally important in Biblical studies as it gives us a look at Canaanite beliefs, and particularly, those beliefs during the time period just before Israelite settlement. What we’ve found are a massive amount of similarities between the two, that have helped in our understanding of Ancient Israel, as well as the formation of the Hebrew religion.
What we have in this verse are actually two deities. We have Dawn, and his son, Daystar. They come from Canaanite mythology. We don’t find Daystar in the Canaanite mythology that is available to us, but Dawn is known. Dawn, in Canaanite myth, was a son of El, the high god. From what we can tell from Isaiah though is that he’s talking about a god who wanted to join the head of the pantheon, but fails. We see this say sort of thing in Ezekiel 28. The gist though is that we have an overreaching god who is expelled from “heaven.”
Side note: Rabbinic commentators would identify this Daystar with the planet Venus (said to be the morning star). And it is very possible that this god, in Canaanite lore was associated with this same “morning star.”
While later translators and commentators, including the church fathers, would associate this figure, Daystar/Lucifer, with the fall of Satan, there is no evidence that the text had to do anything with a Satan figure. Instead, as is clear from the Ugaritic text, we know that Isaiah is referencing Canaanite mythology.
Moving on to Ezekiel 28:11-19. This is somewhat similar to the Isaiah passage, as I hinted at before. J.L. McKenzie, in an article titled Mythological Allusions in Ezekiel 28:12-18, argues that these verses are actually a variant form of the creation story in Genesis 2-3. McKenzie argues that it is a Hebrew native tradition that is influenced with foreign mythology, particularly Canaanite mythology.
Ezekiel is using this older mythology as an allegory between Tyre and Israel. Tyre had a great relationship with Israel to begin with. In Ezekiel, Tyre is the only neighbor that isn’t presented as positing hostile actions towards Israel. In fact, we don’t have any hostility on the part of Tyre towards Israel recorded in the OT. Tyre was instrumental in building the Temple (1 Kings 5-7), and in Isaiah 23:18, we are told that Tyre would be restored and its merchandise would be seen as sacred.
What we are told in Ezekiel 28:5 though is that sinful trade made Tyre fall away from Israel. What Ezekiel is alluding to is that the pact of brotherhood with Tyre gave them a place alongside Israel by association. That’s why we see Tyre being mentioned in the creation story that Ezekiel is referencing. However, what Ezekiel is saying about Tyre is that because of their actions, they are not being cut from God.
In both of those verses, there is no allusion to Satan at all. We do have allusions to ancient Canaanite mythology, and interestingly, we get a glimpse of an alternative creation myth.
Quickly, with Ezekiel 38 and 39, and reference to Gog, there is no suggestion that he is related to Satan or that those verses are a prophecy regarding Satan. As the New Jerome Bible Commentary explains, the indentification of Gog is probably unimportant (we really don’t know who they are), but that Gog instead symbolizes the powers of “evil” that were threatening Israel. In other words, it just symbolized those groups that were seeking to destroy Israel. And it wasn’t a prophecy for later, but more for something that was happening right then.
Jumping finally to Satan. The noun Satan appears 26 times in the OT. 7 of those referred to human individuals. Of the 19 remaining cases, only 3 don’t use a definite article. The other 16 (14 of which appear in Job), literally say the satan. Now, 2 of those 3 instances mentioned appear in Numbers 22:22, 32. There, we have the idea that the Angel of Yahweh is a satan. So out of the 26 mentions of satan, only 1, in 1 Chr. 21:1 is a proper name. In the rest, it is a common noun, meaning something like the Adversary. However, even that passage could justifiably be translated as a satan rose up. It is worth noting that we get the same story in 2 Samuel 24, but there, instead of a satan, we have the stimulus for the census by David being Yahweh.
What we have in the OT is a satan who isn’t connected to some other realm, but is connected with sin. This has led Yehezkel Kaufmann to argue in the Religion of Israel that the Biblical religion of Israel couldn’t reconcile the idea that there was some power in the universe that defied the authority of God. So instead, it transferred the idea of evil from a metaphysical world to a moral realm: sin.
The idea of Satan really begins to enter into the Jewish ideology more when they are exposed to Persian religion, to Zoroastrianism. We can see in the literature written during that time period, in the apocrvaphyl texts, that references to Satan become much more common. This is probably influenced by the dualism from Zoroastrianism. How far this influence goes is debated. For instance, in the one work of the OT that probably should have the most influence from Zoroastrianism, Nehemiah, we just don’t see the awareness to Persian beliefs. It may that the prophets repressed such views. It also maybe that the works we see as part of the apocrypha just represented the quasi-mythology that was widely accepted throughout the time period.
In the NT period, we see the mentions of Satan, or other names used for Satan, really expand. And really we are seeing a parallel to the dualism (or a modified dualism) that we see from Qumran, which is a struggle of massive proportions between the Angel of Darkness and the Prince of Light. But even in the NT, Satan doesn’t have unlimited powers. He can be resisted. God can use him (such as in 1 Cor. 5:5), he is judged (John 16:11), that he is bound (Rev. 20:2) and incinerated (20:10).
So to sum up. In the OT, Satan is not a proper name. Simply, Satan just refers to an Adversary, either human or celestial. But it is not a proper individual. Its applied to many. In the Jewish apocrypha, we see an influence of Zoroastrianism-based dualism, and the mention of Satan really takes off. By the NT times, Satan is a proper individual, but the dualism changes a bit, as we see in the Qumran scrolls. And Satan is limited in power, and will be incinerated. The church fathers will expand on this, including passages such as the one about the Daystar, which had nothing to do with Satan to begin with. But its incorporated into the mythology, and the view of Satan continues to evolve.
