Basically readers make their reading choices, based on the context of course. As far as I know Hebrew has the same issue. All I want to discuss here is that God really ordered the killing or Satan actually did.
I think you answered your own question.
Prior to the 300-400 years of bondage in slavery building monuments in Egypt, one would be hard pressed to find instances of G-d ordering the Hebrews to kill anyone in the Bible. Abraham dug a string of water wells to avoid conflict with the indigenous people, he could have as easily dug in and defended any one of those wells (he might also have lost, if he was outnumbered). I seem to recall an instance where the ten brothers (sons of Jacob) tricked some tribe into getting circumcised because their leader wanted the sister of the ten brothers as a wife. While healing, the brothers snuck in and killed off that tribe - and G-d punished them for doing so, they did not act with His blessing.
After the time in Egypt, they wandered in the desert for 40 years, and when that generation passed away (long story not germane to this specific discussion) G-d led the Hebrews into "the Promised Land." You, personally, could argue that G-d ordered the Hebrews to kill off all these people, but from the Hebrew perspective it was a war of survival - they were a people without a home returning to their ancestral home, the land of Abraham, Isaac and Jacob, to return the bones of Joseph to rest among his kin. Various arguments can be made for and against, just depends which side you are on. Done is done, G-d clearly had a hand in clearing the region for His Chosen People (Red Sea crossing, walls of Jericho as examples).
Later, as the Hebrews got settled and established, they even made peace with some of the local tribes (who presented under false pretense, but the Hebrews were no stranger to this tactic either), something that G-d disapproved of, and later these peace compacts came back to haunt the Hebrews.
By the time of the massacre of Bar Kochba and the dispersal of the remnant of Israel out of their homeland by the Romans, the Jews have not had the political power or force of themselves alone to wage offensive or Imperial war. They have through the centuries (generally speaking with exceptions) served instead to reinforce the militaries of their host Nations. And now, since 1948, Israel is limited to defensive wars.
{{{ Why did Cain murder Abel? The First Murder (Genesis 4:1-16) }}} If this is true, we are descendants of Cain and killing is just fine, a legacy.
G-d did not order this, G-d ordered Cain banished for this, I think it is EASY to connect the dots, even on a surface level. Suggesting G-d told Cain to murder his half-brother is taking things WAY out of context.
And if you look just 2-3 chapters later, Cain is NOT in Adam's geneology, Cain was not Adam's son. There is deeper teaching, not germane to this discussion. Bottom line is that "the people of the Book" are not related to Cain. After Jesus, "the Book" applies to any who seek and ask. But in the story that unfolds in Genesis and throughout the Old Testament, Cain only gets that brief, walk on appearance, he is not related to the people whose history is being told.
