I have a vested interest in this! :-) I was named after my father, whose name was John although he was called Jack. I found the following at
link:
Gender: Masculine
Language: English
Etymology:
Jack is short for Jackin, an alternate form of Jankin, a English diminutive form of John, the English form of a Hebrew name, Yohanan, Johanan, or Yochanan. Originally it meant “The Lord Has Favored,” “Gift of God,” or “God is Good.
-or-
Jack is sometimes thought of as an English form of Jacques, the French form of Jacob, the English form of a Hebrew name meaning “Supplanter.”

History:
Jack was a very common nickname for John (as well as, more rarely, for Jacob). It was so common that it became slang for “man” and is found in many common phrases from “Jack-of-all-trades” to “Jack-o-lantern.” Occasionally, Jack, used as a nickname for Joseph or George, as well as others.

Reading about the Hebrew names--rather, their beginnings, I was reminded of the name Yahweh, for God. So...my name goes back that far?