if I just proved to you that Adam didn't physically die the day he sinned then we can comfortably rule out the sin being a leading cause of physical death.
You didn't prove that "day" means a calendar day. "Day" is used many times in the Bible to refer to a long period of time as well.
Here is an example of Zechariah explaining several events that will happen in a period of time which he refers to as a "day".
(You don't have to read the whole passage, but take note of the bolded text)
“Behold, a day is coming for the LORD when the spoil taken from you will be divided among you. For I will gather all the nations against Jerusalem to battle, and the city will be captured, the houses plundered, the women ravished and half of the city exiled, but the rest of the people will not be cut off from the city. Then the LORD will go forth and fight against those nations, as when He fights on a day of battle. In that day His feet will stand on the Mount of Olives, which is in front of Jerusalem on the east; and the Mount of Olives will be split in its middle from east to west by a very large valley, so that half of the mountain will move toward the north and the other half toward the south. You will flee by the valley of My mountains, for the valley of the mountains will reach to Azel; yes, you will flee just as you fled before the earthquake in the days of Uzziah king of Judah. Then the LORD, my God, will come, and all the holy ones with Him! In that day there will be no light; the luminaries will dwindle. For it will be a unique day which is known to the LORD, neither day nor night, but it will come about that at evening time there will be light. And in that day living waters will flow out of Jerusalem, half of them toward the eastern sea and the other half toward the western sea;
it will be in summer as well as in winter. And the LORD will be king over all the earth; in that day the LORD will be the only one, and His name the only one. All the land will be changed into a plain from Geba to Rimmon south of Jerusalem; but Jerusalem will rise and remain on its site from Benjamin’s Gate as far as the place of the First Gate to the Corner Gate, and from the Tower of Hananel to the king’s wine presses. People will live in it, and there will no longer be a curse, for Jerusalem will dwell in security. Now this will be the plague with which the LORD will strike all the peoples who have gone to war against Jerusalem; their flesh will rot while they stand on their feet, and their eyes will rot in their sockets, and their tongue will rot in their mouth. It will come about in that day that a great panic from the LORD will fall on them; and they will seize one another’s hand, and the hand of one will be lifted against the hand of another. Judah also will fight at Jerusalem; and the wealth of all the surrounding nations will be gathered, gold and silver and garments in great abundance. So also like this plague will be the plague on the horse, the mule, the camel, the donkey and all the cattle that will be in those camps. Then it will come about that any who are left of all the nations that went against Jerusalem will go up from year to year to worship the King, the LORD of hosts, and to celebrate the Feast of Booths. And it will be that whichever of the families of the earth does not go up to Jerusalem to worship the King, the LORD of hosts, there will be no rain on them. If the family of Egypt does not go up or enter, then no rain will fall on them; it will be the plague with which the LORD smites the nations who do not go up to celebrate the Feast of Booths. This will be the punishment of Egypt, and the punishment of all the nations who do not go up to celebrate the Feast of Booths. There will be inscribed on the bells of the horses, “HOLY TO THE LORD.” And the cooking pots in the LORD’S house will be like the bowls before the altar. Every cooking pot in Jerusalem and in Judah will be holy to the LORD of hosts; and all who sacrifice will come and take of them and boil in them. And there will no longer be a Canaanite in the house of the LORD of hosts in that day.” (Zechariah 14:1–21)
Summer AND Winter both occur within this "day" (described throughout the chapter). Since summer and winter are 6 months apart, this usage of "day" cannot mean a 24- hour calendar day. This meaning is used variously throughout the Bible.
So in reference to
Genesis 3:17, you'd have to prove that it means a calendar day (24-hour day) rather than a season of time
(Adams lifetime) before it can legitimately be used to support your theory of the cause of spiritual death, physical death, and annihilation.