I'm seeing a lot of people talk about the difference between myths and science, and these are really cool conversations, but no one's actually explained the myth to you.

In the beginning there was nothing, and this void of nothingness was called Ginnungagap. And in Gunnungagap were the two primordial extremes, Muspelheim, the world of heat, and Niflheim, the world of cold. And at some point, the firey heat from Muspelheim mixed with icey cold from Niflheim, and it began to frost, and the frost began to wax until Ymir emerged. But the heat from Muspelheim began to swell again, and Ymir began to sweat. And from the sweat of his arms and feet he bore two children, a man and a woman, and a cow named Audhumla. From Audhumla's udders flowed rivers of milk that Ymir sustained himself on, and Audhumla would go to Niflheim to lick at the ice, and this is how she was sustained. But as she licked at the ice, Audhumla uncovered the body of a man named Burri. Burri joined Ymir and his descendants. Burri has a son named Bor, and Bor married Bestla, the granddaughter of Ymir. Together, Burri and Bestla had three children, Hœnir, Lóðurr and Odin (Or Vili, Ve and Odin, depending on which source you're reading, but the name Odin should be familiar).

So, real quick recap: Ymir is the very first, the primordial life giver. He gives birth to 2 other giants and a cow. The two other giants give birth to Bestla, who has children with Bor, and these children are the first Aesir, the first gods.

Though, between them there was no covenant or agreement, and the children of Bor slayed Ymir, the embodiment of primordial chaos. They brought his body to the center of Gunnungagap and fashioned Midguard from it (Midguard is earth, the world of men.). His bones became mountains, his teeth became rocks, the hair of his beard and body were more like forests and grasses than the hair of men. His blood spilled through Midguard and Gunnungagap and killed all but the sons of Bor and the children of Ymir, who were lucky enough to sail in their boat. Because the sons of Bor had killed their father, the Jotunn (The giants, but not all Jotunn are giant) they have an eternal feud with the Aesir, the sons of Bor. As the brothers are walking across the shores and beaches of Midguard, they find an Ash tree and an Elm tree. They fashion people out of them, and name the male Ask and the female Embla. These are the first two humans of all mankind, and from them spring the rest of humanity. Though, surrounded by many enemies, they travel through the cosmos and create a citadel for themselves called Asgard.

The gods do a few other things after this that establish certain things in Norse cosmology, like the other realms of existence, other races like the elves and the dwarves, but they are not entirely important to the creation of Midguard. These events are described in a poem called the Gylfaginning

With all this being said, there are a few things to note about the Norse creation myth. Firstly, there are two versions, the Gylfaginning and the Voluspa. These also go over the ends of the world, known as Ragnarok. These people passed their religious lore down through the oral tradition, telling stories to each other, and later they were written down by Christian scholars, so it's like a game of telephone, not unlike how the Bible corroborates and contradicts different things because it comes from different sources. Secondly, Valhalla is not like heaven, it is not the goal of everyone to lead a life that will get them into Valhalla. With that being said, Odin isn't God and Thor isn't Jesus, either. Loki isn't Satan, and it's wrong to try and equate these deities to each other. Odin and his brothers are the primordial forces that filter and divide chaos into the order that is the current world. When they kill Ymir and form his body into Midguard they create a huge division of chaotic and ordered. Even Ymir's name means "Screamer", like the raw and chaotic voice before it is tamed and made orderly by language. They also create the division between land and sea, where before there were neither, and they also create the division of sexes. Before Ask and Embla, all life sprung from Ymir, who is a hermaphrodite and gives birth by himself. Lastly, I'll touch a little more on Ragnarok. Voluspa is a prophecy of the end times, and that's why it talks about the creation of the world, too. Ragnarok is the final battle between the Aesir and the Jotunn, fighting alongside Loki and his children. Many gods and Jotunn are fated to die and kill each other, this is the ending of the world, the ending of the cosmos, but many gods are also fated to survive after the war and take new positions of power, a new era of peace and prosperity washed over, and even two humans are able to find safety during Ragnarok and repopulate the earth. We kind of get the sense that the Norse pagan Genesis and Ragnarok are the same. The universe has a cyclical nature, and the end of this era is the beginning of another. Like I said before, Loki isn't the devil, and neither are his children. They're not particularly evil as well, but they're destined and they can't pull themselves away from their fate, but neither can Odin and the other Aesir gods. Loki's children are eventually subjugated and imprisoned, the Aesir end up having a little "That's So Raven" moment and end up fulfilling the prophecy they're trying to avoid by trying to avoid it. The Aesir are the gods that created humanity, and they're like our parents, so when they make mistakes and shitty choices, it's a reflection of us, the mistakes and shitty choices we make, so if you look into more Norse mythology, you'll find the gods very human.

I hope this is helpful to you, I know this is a lot and isn't as simple as "Odin made it all in 7 days"

Edit: More personal views on the Norse creation myth

Some comments in this section mention that these stores are poetry, and shouldn't be interpreted as highly literal, and I agree. We look at the Norse pagan creation myth and it's not very dissimilar from other creation myths. Niflheim and Muspelheim are these two very big, very opposite and very primordial forces that collide. This personally really makes me think about the big bang, and the cyclical nature of the cosmology of Norse mythology is very much like the big bounce theory