I’d like to think that in some distant past these elements were included by someone who saw the need to preserve that wisdom.
Ragnarök makes a great metaphor, if we take the ‘order vs chaos’ view prevalent in many written sources, for the collapse. Growing tension, coming to a final showdown, and great mutual destruction, but a new age begins.
Thor slays Jormundr, but later dies from the venom which that battle imbued him with. We have ‘beaten’ aspects of nature, but at what cost to ourselves?
Thor’s sons Magni and Modi, will survive the battle, the new gods of an era of peace. Not all is lost, it’s not the end of the world, its the end of an era.
This said, I am unsure about the duality present in the mythology, given the sources for much of the knowledge were Christians who openly undermine many aspects, and related much of it to their own religion.
Most of these sources pit gods vs giants, but forget about the other 7 worlds and other races within them. They give you Valhalla or Helheim, as heaven or hell, forgetting the many halls of the Aesir, and many layers of Helheim, some of which are not even a bad place to be.
Edit: I should also note that the fire giants which ride from Muspelheim destroy all people, except for two which Odin hid away, where else? In the forest.