Gen 32 records a very evocative and enigmatic incident. I'd like to scrutinize the liberal interpretation.
1. On the liberal interpretation (e.g. Gunkel, von Rad, Westermann, Robert Alter, Bill Arnold, H. W. F. Saggs) , Jacob's adversary reflects two different traditions. One tradition concerns trolls that guard crossing-points at rivers. The other tradition concerns nocturnal demons who lose their powers between dawn and dusk. That would explain the riverine setting, as well as why his adversary seeks to break off the attack as dawn approaches. So it has a certain prima facie appeal. There are, however, serious problems with that interpretation:
2. It assumes the redactor combined elements from two different tales or traditions. The troll-motif and the nocturnal demon-motif. Either two different sources or at least two different archetypal characters (trolls and nocturnal demons). These don't normally go together. But the redactor allegedly fused the two characters into one.
In addition, the redactor expunged the overtly pagan elements. In the redacted version, Jacob's adversary turns out to be a theophanic angelophany.
That, however, is a very convoluted editorial process. If, moreover, the narrator is writing pious fiction, why bother with such unpromising material in the first place? Why not write something from scratch, rather than engage in this cumbersome scissors-and-paste procedure?
3. Moreover, Jacob's adversary doesn't play the role of a troll. Jacob crosses the river without opposition at least twice: first to lead his caravan across the river, then to recross the river so that his caravan is on one side while he's alone on the other side (22-24). Indeed, he may have to crisscross the river several times to conduct his entire caravan to the other side. There is no trollish agent that blocks his entree.
As for nocturnal demons, from what I've read (Sarna), the tradition depicts them like Proteus in Ovid's Metamorphosis. But Jacob's adversary is not a shapeshifter. He retains a humanoid form throughout the wrestling match.
4. Furthermore, even though trolls are mythological agents, they may have a basis in fact. Historically, people do guard fords and bridges to collect tolls from travelers. Likewise, fords and bridges would be natural settings for bandits to lie in wait. Travelers on foot bottleneck at that juncture, because that's the only crossing-point within miles up or down the river. So that's an opportune location for bandits to lurk. As such, the mythology of trolls may represent the legendary embellishment of bandits or toll collectors at fords and bridges.
Likewise, traditions of night hags may have a basis in fact. Occultic entities do exist. I don't think that figures in Gen 32. I'm just challenging secular assumptions.
5. If, however, we reject the nocturnal demon identification, then why is Jacob's adversary eager to leave before the break of dawn? Maimonides construed the account as a "prophetic vision" (Guide for the Perplexed, Part 2, chap 62). I assume he means a supernatural dream. It can't merely be a night vision, because the experience is interactive. A tangible as well as visual experience.
Up to a point, that's an appealing interpretation. It's not the first time Jacob had a supernatural dream. Moreover, his first supernatural dream, about angels, took place when he was leaving Palestine (Gen 29). So it would form a nice inclusio if he had another dream, about angels, upon reentering Palestine. It would also explain the urgent distinction between night and day. If his adversary is a character in a dream, it would vanish the moment he awoke.
However, an impediment to that interpretation is the fact that Jacob is injured during is wrestling match. While it's possible to experience pain while dreaming, or have a simulated injury while dreaming, that only exists in the dream. It disappears when you awaken. Yet Jacob was objective injured.
Mind you, it's possible to injure yourself while you sleep, if you thrash about. And it's possible that hurting yourself when you're in bed prompts you to dream about hurting yourself. But as far as Gen 32 is concerned, that's backwards.
6. There's a bit of playacting on the part of Jacob's adversary. He pretends that Jacob is a well-matched opponent. He lets him feel that Jacob has the upper hand. But then, with a mere touch, he injures Jacob, demonstrating that in reality he was just toying with Jacob. All along, he could effortlessly overpower Jacob if he wanted to.
7. It may well be that Jacob's adversary chose a night-time setting to conceal his true identity under cover of darkness. The initial anonymity creates suspense, preparing for the last-minute recognition scene.
8. In addition, you have the familiar theme that seeing God face-to-face is potentially fatal to humans. The night-time setting would prevent that lethal exposure.
To be sure, that's a somewhat puzzling or paradoxical hazard, since the Pentateuch does have examples of men who "see" God and survive to tell the tale. I think that tension trades on degrees of exposure. In this case, the divine encounter is mediated by the Angel of the Lord. To see God in the person of the theophanic angel.
In what sense is it potentially fatal to see God? Two possibilities suggest themselves. One is cultic holiness, like touching a ritually pure object (e.g. the ark of the covenant). It's not that the object is intrinsically toxic. Rather, God strikes the person dead as a warning. The other possibility involves a vision so terrifying that it triggers a heart attack. It's possible to be literally scared to death.