Yeah...
Now I don't like to give any answer to such an old thing, but here it is: What you cite is the Nineveh's version of the traditional Babylonian Epic of Gilgamesh. But what you have to see first is that the Epic per se comes in several versions (included partial Hittite ones, somehow different) and the Epic is borrowing from older traditions. Here is the Sumerian:
Huwawa the ogre
The Sumerians built in their time 2 great cycles/stories/matters/epics (call that as you want, I will use cycle here). The first cycle is the cycle of Aratta which detail the relationship/war between the city of Aratta and the city of Ur. One of key characters is the hero Lugalbanda (who is the father of Gilgamesh). The second cycle is precisely the cycle of Gilgamesh. And in this cycle one of the deeds of Gilgamesh is his fight with a specific ogre like creature Huwawa (the Sumerian version of the Babylonian Umbaba).
The story goes like this: Giglamesh decides to visit the forest of cedar with his friend/budy/slave Enkidu (in this story Enkidu is referred as slave). When they arrive there, they fall asleep, all except Enkidu. He manages to get Gilgamesh to wake up, and Gilgamesh is seriously pissed off. Enkidu tries to calm him, but without success, knowing what lies behind.
There they finally discover the source of the problem: The ogre Huwawa who is surrounded with no more that 7 auras of terror... And then the thing become amusing, judge:
[Gilgamesh says to Huwawa:] No one really knows where in the mountains you live; they would like to know where in the mountains you live. Here, I have brought you En-me-barage-si, my big sister, to be your wife in the mountains.
This passage does seem pretty serious. Except when you know who is the so called Enmebaragesi, which in matter of a potential Gilgamesh's cute sister is the former king of Kish, father of Ata, arch enemy of Gilgamesh! Appreciate Sumerian humouresque side and Gilgamesh's fainting of terror.
So Gilgamesh will keep mocking up the poor Huwawa by offering completely stupid gifts each time removing one of his terror until the moment Huwawa has nothing left. Then: [Gilgamesh] made as if to kiss him, but then punched him on the cheek with his fist. And thus: Ḫuwawa clutched at Gilgamesh's hand, and prostrated himself before him.
Then you have the final reversal:
Huwawa addressed Enkidu: "Enkidu, you speak such hateful words against
me to [Gilgamesh]!" (...) As Ḫuwawa spoke thus to him, Enkidu,
full of rage and anger, cut his throat.
So that is the original [abridged by me] story (at least in one of its versions). The important elements are:
- Huwawa stripping its power (reminiscent of Inanna's stripping of power when she tried to rule the Abzu (Hell)). Notice something truly amusing, Gilgamesh stays perfectly calm in front of him and manages to abuse Huwawa pretty easily, despite the auras of horror.
- Enkidu's reversal attitude: He starts by doing his best to wisely prevent Gilgamesh to go to see Huwawa and finally is the one slaughtering the poor Huwawa
- Huwawa which is presented as an horrifying monster but just seem a lonely naive creature who believed Giglamesh a little bit too fast (Once again Inanna will fall to such a trick).
There are variants both in Huwawa's story and Humbaba story of the way he is killed but that is merely details.
Huwawa's death variation
Let me show this Huwawa's death variation:
- [Huwawa:] "Warrior, you lied! You have manhandled me; yet you had sworn an oath"
[Gilgamesh] addressed his slave Enkidu: "Come on,
let us set the warrior free! (...) He could be our guide who would spy
out the pitfalls of the route for us!" [Enkidu]: "A captured warrior
set free! A captured high priestess returned to the ĝipar! A captured
gudug priest restored to his wig of hair! Who has ever, ever seen such
a thing?"
In this version (the one of the Epic so) we see Enkidu this time truly pleading for Huwawa's death. We don't have the end, but it is very safe to imagine that it is like the Epic and Gilgamesh will slaughter Huwawa. But in all aspect Enkidu in both version is directly responsible of Huwawa's death.
Mesopotamian myths
Now, truly understanding Mesopotamia's time is hard (Leo Oppenheim mentioned that having a vision of Mesopotamian religion is illusory at best, while doing it in the same book anyway). Mesopotamia is full of ambivalence. Inanna (Ishtar) is probably the best example. Her interventions during the cycle of Aratta is emblematic of that. This is to the point you start to ask yourself what she does exactly, because when she finally sides with Ur, Enmershikar is almost already victorious. To the point you see she sides with you when you have so proved yourself to her that you ask yourself why you would even need her help! I give you this short insight here on Inanna just because it shows the Mesopotamian subtlety. This beautiful subtlety is all around the Huwawa story. Huwawa is truly terrifying and still it is difficult to not feel sorry for him. Gilgamesh seems totally immune to Huwawa's power, when Enkidu has proven resisting better than Gilgamesh, still you see Gilgamesh trying his best to strip Huwawa's power. At no time does the text makes Gilgamesh emphasize how he is mocking Huwawa, but a remote knowledge of Sumerian myth makes that clear (I mean... EVERY Sumerian was undoubtedly laughing when Gilgamesh propose Enmebaragesi as a wife). Enkidu at first sage, wise and scared, actually slaughters the poor Huwawa out of rage. You have lots of Sumerian themes beginning by the reversal which makes a story begin with one character (as the legendary king Enmerkar) and keep going with another character (the hero Lugalbanda). You have such a typical example here where the story lets you believe that Gilgamesh will do the job, when Enkidu actually slaughters the monster. It is reminiscent of one of Sumerian favourite stories, the dialogue/dispute: 2 things/characters fighting to know which/who is the best.
Let me finish by giving you this insight into Mesopotamian literature. We have a letter sent by a son to his mother while she is without news. The letter contains an incredibly long description of the mother in order to help the messenger to find her. 50 lines. Then comes the text of the letter, appreciate:
When thanks to the descriptions I have given you, you stand in her
radiant presence, tell her: "Your beloved son, Lu-dignira is in good
health".
Appreciate here the incredible beauty of Sumerian poetry "Lu-dignira is in good health"...
Epic of Gilgamesh
The Epic of Gilgamesh is a Babylonian story so one might ask why I spent so much time on the Sumerians, Sumerians being a different people, speaking a different language. Out of the 5 stories of the Sumerian cycle of Gilgamesh, 3 are core elements inside the Epic, and the Epic out of that simply borrows freely inside Sumerian lore. The key character Uta-napisthim being no more than the Sumerian Ziusudra as an example. Babylonian intellectuals, using the Sumerian cuneiform writing system, was nurture by Sumerians. To the same extend than modern occidental world is nurture by Romans and Greeks.
The Epic so built on that Huwawa story:
- You find Enkidu, still alive, warning Gilgamesh non-stop about the danger of Humbaba.
- The fight is presented differently, as the writers noticed Huwawa does not seem so terrible and made the episode longer and Humbaba a little bit more scary (this time Gilgamesh needs the help of his mother, he cannot simply openly mock the poor Huwawa).
But basically Humbaba being Huwawa ought to die. Huwawa received no mercy, Humbaba has the exact same fate. Enkidu, who was wisely preventing Gilgamesh to not face Huwawa, will do the same, and with same consequence he is utterly the one directly responsible of Huwawa/Humbaba's death. Gilgamesh and Enkidu will face the wrath of Enlil because in the original story they did.
Now the Epic of Gilgamesh per se is on a different level than the Sumerian cycles. For example, the cycle of Aratta is formed of 4 stories. In the first one, the dispute between Ur and Aratta is solved via diplomacy when in the other 3 it is war. In all case, Aratta's defeat is there. But those are disconnected story. The Epic is a full story.
On poetic term, Huwawa story is a short piece of 200 lines when Humbaba story is evolving around 3 chapters. In Huwawa story, Enkidu is clearly shown as the direct responsible of huwawa's death, the Epic makes that slightly less clear (very cleverly). In Huwawa's story Enlil is not very happy that Huwawa was murdered, in the Epic, Enkidu will pay deeply those constant misbehaviours because just after he will kill another innocent monster Gugalanna. And then only Giglamesh will go on a (semi) purely Babylonian part trying to vainly trick death.
I tried to show here the Sumerian root of the Epic, how the Sumerian elements has been taken, incorporated and developped for the Epic. The Epic of Gilgamesh is the very first epic ever written and on that comparing the disparate relatively shorts stories that form the core elements of the Sumerian cycles is unfair to both. But it shows how the writter(s) of the Epic took its(their) lore, built on it, and added the local faith (the totally absent Sumerian gods play a major role in Babylonian culture). It also shows how to make a proper "remake". No doubt that Homer did something similar in his time (No doubt also those who judge Homer as mere guy compulsing traditions are mere idiots).