Norn and norn-related stuff have influence from norse mythos. This was even heavier in Eye of the North.
Sylvari and sylvari-related stuff have influence from Celtic and Arthurian mythos.
Charr and charr-related stuff have influence from Greek and Roman cultures (but not mythos), charr history having influence from Mongolian culture and history.
Asura hold some influence from latin, particularly in their city naming and the Elder Dragon they contended with (Primordus). One can also find Mesoamerican influences amongst their architecture.
Humans take from a myriad of different cultures, depending on the nationality of the human. Orr takes from Arabic (as do Largos), while Vabbians appear to have more Persian influences, Ascalonians being more medieval northern European, etc. etc.
Each of the minor races tend to take influence from a specific culture or mythos as well – though some like krait don’t seem to take from any culture or mythos. Hylek take from Mesoamerican (Aztec, Miyan, Incan) for example.
Trees being literal doorways to other worlds, especially white oak trees (which the Pale Tree is per The Movement of the World) was a common theme in Celtic mythos, and they often served as home to lower gods such as the Fae (now commonly called faries – but don’t let Tinkerbell fool you, Celtic Fae were no kind beings). This is tied to the sylvari in the Pale Tree being a metaphorical doorway into the Dream. The Nightmare Court were also inspired by the Unseelie Court – basically downright evil Fae who opposed the Seelie Court (I am dumbing it down greatly).
In another myth, when one of the Gods (Thor) kills the midguard serpent, the world ends, and all the Gods and Giants die. Only the Aesir (Elves), survive.
That’s rather off from how I’ve read it.
Thor and Jormungandr face off during Ragnarok – which the final battle between the Aesir (the Asgardian gods) and the forces of Sutr and Loki and Loki’s children (Hel, Fenrir, and Jormungandr). During said final battle, Odin was consumed by Fenrir, and Thor and Jormungandr kill each other in battle (Thor killed Jormungandr but the poison from the midgard serpent ended up killing Thor shortly after). Near the end of the battle, Sutr with his flaming greatsword burned all existence, leaving only the Yggdrasil untouched. With suspect of tampering by Christian monks, the story then goes on to say that all that survived the battle were two humans, a male and a female, that took shelter in the boughs of Yggdrasil.
Again, this is a fairly brief summary and skips over a lot. And it should be noted that there will be variances depending on who translated the texts. There’s seldom a word-for-word transcription, and there’s often cases of the translator embellishing the tales to make them flow better while still staying to the original mythos.
The elves were not the Aesir, but were the third group of societies living on the highest of the three planes (there were 9 worlds/realms, but 3 planes in which these worlds existed on, each plane having 3 worlds; the highest plane was home to the elves, the Aesir, and the Vanir; the middle plane was home to humans, jotun, and dwarves (aka dark elves – they were one and the same in norse mythology); and the lowest plane was home to Hel and those who died of sickness and old age).
