Some more verses to consider in which taken are the wicked ones, "none is left", as in destruction, and taking as spoils of prey in war. This same attitude translates to spiritual war, God always treats the wicked in the same way, they are taken and none is left.
Deuteronomy 2:34 And we took all his cities at that time, and utterly destroyed the men, and the women, and the little ones, of every city, we left none to remain:
Joshua 10:37 And they took it, and smote it with the edge of the sword, and the king thereof, and all the cities thereof, and all the souls that were therein; he left none remaining, according to all that he had done to Eglon; but destroyed it utterly, and all the souls that were therein.
1 Samuel 17:20 And David rose up early in the morning, and left the sheep with a keeper, and took, and went, as Jesse had commanded him; and he came to the trench, as the host was going forth to the fight, and shouted for the battle.
Job 39:25 He saith among the trumpets, Ha, ha; and he smelleth the battle afar off, the thunder of the captains, and the shouting.
Numbers 31:53 (For the men of war had taken spoil, every man for himself.)
1 Samuel 27:9 And David smote the land, and left neither man nor woman alive, and took away the sheep, and the oxen, and the asses, and the camels, and the apparel, and returned, and came to Achish.
Jeremiah 51:56 Because the spoiler is come upon her, even upon Babylon, and her mighty men are taken, every one of their bows is broken: for the LORD God of recompences shall surely requite.
The dead body may refer to both believers and the unbelievers. Since the unbelievers didn't accept the death of Jesus, they died themselves at the pouring of judgment of God upon them "in the cup which she hath filled fill to her double", while the believers accepted Jesus drinking the cup of wine of wrath of God. So whatever is slain, it's probably safe to conclude the dead body is slain as a result of pouring of the wrath of God since the whole part is about separation of saints and sinners, and judgment of God.
In many places in the Bible it's emphasized that "not one left" of the wicked, or similar descriptions to that effect.
The left is probably the righteous. Left as in spared, otherwise it would imply some kind of abandoning or leaving behind, which makes little sense. God acts more straightforwardly than that.
I'm leaning towards understanding that the wicked are taken.