Rage and its consequences
Achilles' rage is the engine of the plot. It starts with wounded pride, causes him to abandon his allies, leads to Patroclus' death, and then transforms into grief-driven violence. The poem tracks what happens when one man's anger goes unchecked.
Honor and shame
Every major character measures himself against public reputation. Agamemnon cannot back down without losing face. Achilles cannot accept the insult without losing status. Hector stays to fight Achilles partly because he is too ashamed to retreat inside the walls. Honor drives decisions that get people killed.
The humanity of the enemy
Homer gives the Trojans full inner lives. Hector's scenes with his wife Andromache and his baby son Astyanax make him as human as any Greek hero. The poem refuses to let either side be simply right or simply wrong.
Mortality and the brevity of glory
Characters on both sides know they will die. Achilles knows his death is coming soon after Hector's. The poem keeps returning to how short life is and how quickly glory fades. That awareness shapes how every hero fights and chooses.
The will of the gods versus human choice
Zeus, Athena, Apollo, and others shape outcomes, but human characters still make choices that matter. The tension between divine fate and personal decision runs through the whole poem. Heroes act knowing the gods may override them, and they act anyway.