DC I realise you prob think this point is so obvious that it is beneath you to do more than a one word hit and run job - but I invite you to actually go into the matter and discuss openly. It is not as black and white as you may think.
You have quoted CCC 400: (Concerning original Sin)
“… Finally, the consequence explicitly foretold for this disobedience will come true: man will “return to the ground”, [285] for out of it he was taken. Death makes its entrance into human history.”
This statement does not actually contradict the ancient Catholic belief of the Fathers that Adam naturally aged even in the Garden and in time also would, without intervention by God, have died. Possibly something akin to the Dormition of the Virigin.
The reason why you may think this indirect passgae from the CCC makes the opposite point is possibly due to mistaken logic. Death of the body as a consequence of disobedience to God (the original sin) is not the same thing as immortality of the body due to non-disobedience to God.
What you may have forgotten to consider is the external gift of immmortality symbolised by the Tree of Life. This, according to the Fathers and Aquinas, was what would have enabled Adam to counter the internal,natural, constitutional mortality of his body present even in innocence.
Note two very important things re the TOL in Genesis:
(1) God commanded Adam not to eat of it even before he sinned. Thus God effectively subjected Adam, even in first innocence, to eventual death. That is God’s right by law and by nature. God never gave Adam an “irreversible gift” of bodily life by making him naturally, intrinsically (and hence irreversibly) immortal.
However it is clear that God may well have been preparing Adam to be allowed to eat of the TOL if he proved himself obedient and responsible. Thus Adam could have attained effective, extrinsic bodily immortality when God dropped his arbitrary ban on eating regularly of that TOL as a remedy against Adam’s intrinsic (but slow) mortality. But such immortality from the TOL would clearly be due to ongoing and arbitrary generosity of God - it was never Adam’s intrinsic right.
(2) Adam disobeyed God and was driven from Eden. Barred from Eden (and the TOL) the immutable law of death was imposed on Adam and his offspring when he was removed from Eden. So eventual death, which was not God’s original plan for Adam (had he stayed in Eden), inevitably followed. In addition, human bodily nature (always essentially mortal) became more distant from the soul - making death/corruption much more powerful in the body than was the case in Eden (even without the TOL). It is interesting that in the Old Testament we see the first men as very vital (living hundreds of years) and with time and further sin man is seen as living shorter and shorter lives. De-evolution. Adam (before sinning)even in his natural mortality, and without eating of the TOL, would have lived a very very long time.
If you go into this matter more deeply than you have I believe you will discover that the above is the general consensus of the Church Fathers.
Therefore bodily life in this world is not a human right before God. And He is not unjust if he arbitrarily decides not to extend it or even decides to take it back. Its like the story of the day workers in the market place. Is the Landowner unjust if he freely decides to overpay some and not others?
Whether God ever truly gave a direct command to his Chosen People to kill others to get their way…I have my doubts. Or it may be a case similar to Moses and divorce, it was never meant to be thus but was necessary due to the hardness of hearts.