Serpent's Curse and Cain's Lineage

In the Book of Genesis G-d curses the serpent to crawl on his belly. What is the Hebrew word used for the Serpent? Does the word serpent in Hebrew change after this curse? Prior to being cursed, does the serpent have legs or perhaps wings? What is the word for serpent that is used? Is it נפש? Also is it אלהים or יהוה that is the one who curses him? Also is Cain only a half brother of Abel? The name Tubal Cain means offspring of Cain, correct? So Seth is not his forefather. Are there any scriptures that imply that Cain is not the son of Adam? Thank you for your time. I look forward to your response. שלום

Thank you for your intriguing questions.
The Hebrew word used for the serpent in the Book of Genesis is "Nachash" (נחש), as mentioned in Genesis chapter 3, verses 1 and 2. To differentiate between the serpent before and after the curse, commentators refer to the serpent as "Nachash HaKadmoni" (נחש הקדמוני), meaning "the original serpent."

Before being cursed, it is suggested that the serpent had legs and was capable of walking. The commentator Ibn Ezra adds that the serpent could even speak, though this is disputed by some who argue it did not actually speak; rather, Satan spoke through the serpent, using it as a conduit.

Cain and Abel were full brothers, sons of Adam and Eve (Chavah), as noted in Genesis chapter 4, verses 1 and 2.
Regarding when Hashem cursed the serpent, the text uses "Hashem Elokim" in Genesis chapter 3, verse 14, indicating a combination of mercy (Hashem) and judgment (Elokim). Rabbi Samson Raphael Hirsch elucidates that this combination suggests the curse was not merely punitive but also educational, meant to correct the serpent's behavior in a merciful manner.

The term "Tubal-Cain" (Genesis 4:22), according to Rashi's commentary, is derived from the act of "improving" (similar to the word "tibul," meaning to season or spice), in reference to the enhancement of murder through the invention of weapons. This name does not suggest lineage but rather an association with Cain's act of murder and the subsequent development of tools for violence.

There are no scriptures that explicitly imply Cain is not the son of Adam. The narrative presents Cain and Abel as the direct offspring of Adam and Eve.

• The Book of Genesis, chapters 3 and 4.
• Commentary by Ibn Ezra on Genesis.
• Commentary by Rashi on Genesis.
• Teachings of Rabbi Samson Raphael Hirsch on Genesis.