Well, one thing to keep in mind is that in the ancient world, myths were interpreted very differently. A modern audience looks at the conception of Sleipnir and doesn't know what to make of it, but to an ancient Norseman, it would have carried deeper symbolic messages that spoke to how his culture viewed the cosmos. To understand myths, we must understand the people who developed them.
I admit, I am not well-versed in matters of Norse mythology; given the course you just took, you are likely more learned in I in this area. However, I do know some things about other mytho-religious systems. Consider the ancient Near East, a region that produced the Bible, the Enuma Elish, the Atra Hasis, the Epic of Gilgamesh, the Story of Sinuhe, and many other pieces of mytho-historical literature. Reading these stories on their own in our modern context, they appear to be little more than stories, or the fantasies of an unscientific age. But to do so would be a terrible mistake, because it would ignore how the people in the ANE saw the world. Indeed, while diverse, there were many common threads in the mindsets of these cultures:
- They did not differentiate between physical and metaphysical as we do. To them, what we consider the physical world was merely a reflection of a deeper underlying cosmic symbolism, because to them ontology followed function. Indeed, they would consider myths to be more "real" than their own physicality.
- Mythic narratives were largely allegorical in the sense that they articulated a cosmic pattern. They saw gods in nature itself and the patterns manifest there, and weaved stories that personified those forces to make sense of the patterns they saw. The question of whether or not the forces of nature were actually humanoid beings who fought each other or did things that seem impossible to us would have been mostly irrelevant/missing the point to someone from the ANE.
- Creation (both mundane and divine) was an act defined by separation of previously-united elements and giving things names in order to define their domains and limits. Conversely, chaos was represented by a lack of division.
- Histories were not journalistic, inasmuch as the ancients were more concerned with outcomes than they were substantiating evidence or details; those things were effectively window-dressing and prone to change with the telling. (Consider that the next time you see something in the Bible that doesn't seem to make sense :P)
- Histories were also written primarily as propaganda tools, specifically to legitimate a ruler in the eyes of the gods so he could gain their favor or avoid their ire (in the case of the Israelites, this meant legitimation of the Covenant). And just like modern politicians they spent a lot of time divorcing themselves from the actions of predecessors deemed unfit (Israel was again anachronistic in this regard, as they reserved a LOT of criticism for kings past and present). History was the realm of the divine, and the rise and decline of kingdoms and dynasties were treated as decisions of the divine assembly.
Consider the myth of Noah's flood, itself one of many flood myths in the region (many details borrowed from the Epic of Gilgamesh). The ancient Israelite view of the makeup of the world was in line with the rest of the ANE. Namely the world as they knew it a great stone disk several thousand miles across, bordered above and below by a solid sky and underworld respectively. These elements were surrounded by a great chaotic ocean, which was the source of all water; indeed, rain was believed to be water flowing through cracks in the ceiling that was the sky. Remember how I said that creation involved separation and naming? Most creation myths in the ANE open with a seething chaos that has not been defined as sea, earth, or sky yet; it is all of these and none of them. Order was established by pulling them apart, labeling them, and establishing barriers so that an ordered world can be established. That sea remained, ever ready to swallow the emergent order and return all existence to singular shapeless potential. In this light, flood myths are not actual historical records of global floods but accounts of the gods dropping the barriers that hold chaotic forces at bay, and thus destroy creation.
Not surprisingly, the Noah version of the ANE flood myth meme was structured a bit differently than those of their neighbors. Other traditions usually had a sympathetic god or two sparing a handful of humans and animals while appealing to the divine assembly for mercy. However, the threat of further floods remained, whether due to divine wrath or cosmic catastrophe, and such floods were believed would ultimately end the world. But in the Noah account, Yahweh makes a point of reestablishing the laws of nature thus upset, (fecundity, vegetative growth, etc.) and promises humanity that the aforementioned barriers will never be brought down again.
I'd give you more examples for this region, but I loaned my primary references to a friend recently ^^;