The death spoken of in Romans 5:12 is spiritual death. The death spoken of in 1 Corinthians 15:21 is physical death.
Highlighted area are mine for discussion ~RB.In fact, neither physical death nor spiritual death is the result of Adam's sin. Physical death is an integral feature of this physical creation. There is no such thing as physical immortality. Adam died physically only indirectly due to sin. He died physically because God ejected him from the Garden of Eden where he would have had access to the tree of life which would have extended his physical life indefinitely (Gen 3:22).
While I would agree with your first statement, your second is a flat out contradiction of your first! Paul through the Holy Ghost said that sin:
1st Corinthians 15:21
“For since by man came death, by man came also the resurrection of the dead.”
Physical death came by man, (also spiritual per Genesis 2:17, neither by being an integral part of God's creation, God didn't create evil in this sense ~ only by knowing that it would come, did He create evil.
Isaiah 45:7
“I form the light, and create darkness: I make peace, and create evil: I the LORD do all these things.”Genesis 2:17
“But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.”This took place immediately when Adam sinned. Physical death followed many years later. You said:
Which you should have said: there was "no such possibility", which would have been true, since God alone is immutable, not angels, not man.There is no such thing as physical immortality.
I do not have time much this week for very mush forum time, since I have so much to do for a group of believers who need my assistance for the next four Sunday, the Lord willing. I'll see what I can do, this (forum time) is more for relaxing than very much work as far as studying, and preparation.