Now getting to the creation of the serpent in the Garden of Eden. The creation account refers to a physical creation and not to the creation of cherubim or seraphim, which are not physical creatures, but spiritual creatures.
Lucifer, a.k.a. Satan, was a cherub at the throne of God before the creation of any physical world. Satan entered the physical serpent in order to tempt Eve to sin against God. So in the case of the verse you quoted in Ezekiel 28 that "day" may not represent a physical 24 hour day as we know it because it is not specified in the way the days of Genesis 1 are specified. So that day could cover a period or era before the physical creation.
Your objection that day
in Ezekiel 28:13 and 15 is not that strong.
The Hebrew word translated "day"
in Genesis 1:5 (twice), 8,13,14,16,18,19,23,31,2:2
refering to the seven days is the same word for day in Ezekiel 28:13 and 15.
Strong Exhaustive Concordance Hebrew Dictionary entry # 3117.
Now you may insist that the mention of evening and morning precludes that only a solar day could be meant in Genesis 1. However, by a similar logic "You were perfect in your ways from the DAY that you were created ..."
does not insist that AGE has to be understood there. Rather liturally on the solar day he was created he was perfect in his ways.
Similarly "The workmanship of your tambourines was prepared with you on the DAY that you were created"
does not insist that an AGE has to be understood there. Rather it certainly could be that on that solar day both the anointed cherub AND the musical instruments accompanying him were both created and prepared at that same point in time.
The word of God is infallible. Our interpretations of the word of God are not infallible.
And in the end of the first century AD and the beginning of the second century AD Hebrew reading rabbis had no reason to be concerned with harmonizing Scripture with Evolution theories which did not exist yet. Nor had they concern to accomodate Scripture to geological theories which also did not exist. Neither Geology nor Evolution Theory had been thought of yet.
However, some Hebrew reading and writing scholars understood that prior to the earth being seen waste and empty God had overthrown previous worlds. And such was found written in The Book of Light or Sefer Hazzohar attributed to one Simeon ben Joachai a disciple of Akiba ben Joseph who [Akiba] was executed in 135 AD.
In this work we see the opinion held towards the end of the first century and the early part of the second century. In this work there is a comment on Gen. 2:4-6 which, though difficult to follow, reads thus:
"These are the generations of heaven and earth ... Now wherever there is written the word 'these' ... the previous words are put aside. And these are the generations of the destruction which is signified in verse 2 of chapter 1. The earth was Tohu and Bohu. These indeed are the worlds of which it is said that the blessed God created them and destroyed them, and, on that account, the earth was desolate and empty."
This is Hebrew Bible exegesis in the end of the first century and early second century AD.
Without concern for concocting billions of years these readers simply understood that Genesis was refering to previous worlds being judged by God.
Also in the Targum of Onkelos of the early part of the second century AD the translation into Aramaic of Genesis 1:2 reads - "w' areteah hawath tsadh'ya"
. This Arthur Custance informs us this translation uses a passive participle of a verb which itself means "to cut" or "to lay waste".
We have here, therefore, a rendering "and the earth was laid waste", an interpretation of the original Hebrew of Gen. 1:2 which leave little room for doubt that Onkelos understood this to mean that something had occurred between verse 1 and verse 2 to reduce the earth to this desolated condition.
[Arthur Custance, Without Form And Void, Doorway Publications, pg.15]
As long as we are trading scholars opinions, include this also in your considerations.