A couple/few things that might clear up your confusion and help you "see", dear Jam (peace to you!):
1. There was no snake in the garden; there was a "serpent"... which is a "seraph"... a "fiery, flying serpent"... which is a spirit being;
2. Adham didn't become literally "like God" by eating from the Tree [of the knowledge of good AND bad]; he was already LIKE God, having been made in God's image. He became "like God... KNOWING good AND bad"... meaning, KNOWING... life... AND death... and yet, still living... something only God... and other spirit beings... "knew" at the time. Because Death has NO hold on God... or spirit beings. These do not die - and that latter must be destroyed (which can only be done by "fire" - HEAT (energy/light) generated to a degree far beyond what is known in THIS world) in order to no longer exist.
3. Eve was deceived into thinking that she COULD become like God... KNOWING good (life) AND bad (death)... and yet, live. Adham, however, was not. Rather, when he saw that Eve did NOT die... he tried to BUY that ability... FROM Death (via an agreement "mediated" through the Adversary, the seraph YOU know as "serpent", who is the "chief agent" of Death)... by selling his progeny: ALL life unique to OUR genus/species... that was generated THROUGH him...
4. Adham/Eve "became" like God (knowing life AND death)... through unsanctioned means. Rather than waiting for GOD to elevate them to a point where they COULD know good (life) AND bad (death)... and NOT misuse/abuse that ability... they reached out and tried to take it for themselves. They obviously weren't mature enough, however, to have that ability. Indeed, Eve's being deceived... and Adham selling out his progeny as well as attempting to throw Eve under the bus afterward... shows this. Imagine what the two of them could have... WOULD have... wrought in the earth if indeed they had gotten back to the Tree [of LIFE]... and ate... so AS to live forever? For one, they would have joined with others... and sought to destroy the SEED [of the Woman] that Eve was carrying! Like that "serpent"... they would have desired the inheritance for themselves (well, Adham would have... and ditzy Eve would have followed him). But it wasn't his to have. Just as it wasn't ISHMAEL'S (the firstborn, from Hagar, the slave woman)... but ISAAC'S (the firstborn, and only-begotten son... of SARAH).
Hagar represents the physical realm... and "earth"... AND the covenant pertaining to the flesh. A covenant made by means OF the flesh (thus, circumscision). Her children, starting with Adham... were and are slaves.
Sarah, on the other hand... represents the SPIRIT realm... "Jerusalem Above"... and the covenant pertaining to the SPIRIT. A covenant made... by means of a PROMISE (and thus, "circumscision" of the HEART). Her children, starting with Christ... were and are FREE.
If man, whose years are now 70 or so... dominates his fellowman as he does... even to his own injury... IMAGINE what would have resulted had this partially "completed" man "Adham" lived without death in his future? Worse than what was wrought by the offspring of the Nephilim!
5. God didn't give us the Bible to "reveal the reality of satans plan and Gods counter plan". He gave us His Son. And so long as folks overlook that Son... due to their inability to look PAST the Bible... they will never see him. And as a result, they will never see God. Or His plan... and/or the events that led up to it, are playing out in and about it... or the end result of it.
6. That "serpent" absolutely DID have free will... and was made perfect. The rotteness came to be in him... because HE put it there, not God: Ezekiel Chapter 28
I hope this helps and, again, I bid you peace!
A slave of Christ,
SA