Thank you Hal, but your post does not answer any of the questions.
God does not babble. When he says something, he is right on the point. In Genesis 3:15, he is talking about Satan's seed. Satan was not cast down with the angels in the rebellion. He was cast out of Heaven later.
Satan did something. Look in Genesis 5 Read the name of Adams first child...do you not find it strange that neither Cain, or Able are listed?
If the fruit was a real fruit, and they ate it...the fruit would have killed them...it did not. Adam, and Eve died because God condemned them to death. Those two trees were symbolic.
Each of us has a family tree.(symbolic.) We are also part of the human tree. (symbolic.) Animals are of the animal tree.(symbolic.) Jesus said he was the tree of life. (symbolic.)
Here is a point; animals always died. When God commands his servants to do something, and they refuse, he forces them to do what he commands, and there is always consequences with it.
When the angels refused to serve man, God cast the down to Earth to serve man...guess what the consequences were? Knowing God, he made them into a form lower than man, but higher than the animals...which means they would have seed. There are scrolls not a part of the Bible that says what Satan did...some are a part of the Dead Sea Scrolls. Satan used one of these angels to beguile Eve. The old word for beguile is intercourse. You think maybe that is why Cain, and Able are not listed as Adams children?
Animals always died. If the human family was injected with animal seed, we would die. Perhaps that is why God called Satan a murderer?
If Adam and Eve disobeyed God, the angels would no longer have to serve man.