The full history of Daémon is long, but punctuated by many points where knowledge has been lost. Most notably and recently is at the launch of the Fleet, where the databank holding much of the knowledge of the Dead World broke.
At the standard point where glowfic threads start, the fleet has been flying for 208 years, and has 83 more before reaching their destination.
(These are in order from most to least recent)
In The Last Century
Relatively little has happened in the past 100 years. Technology has stagnated, due to a lack of free materials. There are no major political schisms or causes for fighting. People are kept reasonably content and busy and as entertained as possible while the ships head forward in order to avoid despair or people picking fights in large-scale. All people have the basics to live on, with a few having excess.
Culture has slowly progressed. Sense discrimination has been illegal for over a century, though the acceptance culturally had been slower and only recently have the last few holdouts of the old beliefs finally died off.
Openly, FTL research is the most important thing. There is also an initiative to find new ways of using the producible materials to replace finite materials in technology. There is a secret illegal lab studying other things, which has access to interdimensional tech and the ability to put daemons on those who don't already have them.
There is the usual slow cycling of media trends, fashion, musical genres, etc.
The Century Rebellion
At the end of the first century there had been resentment and discontent building up, centered around three major poles: Inequality, reproductive demands, and sense discrimination. This eventually boiled over into what became known as the Century Rebellion, lead by an Arceus Legendary.
As a result, noble houses were eliminated as a legally recognized phenomena. The government was restructured so that what had originally been handled by the nobility were now elected positions. The very wealthy were forced to divide their large manors into many smaller apartments, and a large number of restrictions were placed to insure that wealth inequality was less from that point onward, and the funding for decorating and maintaining the Halls and other public things such as schools and hospitals became equal between residential halls rather than on a per-Hall basis which concentrated the funds towards Halls where the nobility lived.
The post-rebellion government set up the Continuation Initiative - a system in which people would be rewarded for having children rather than being punished for avoiding it. People would receive payment from the government for bearing, donating gametes, and/or raising the first two children with a given person's genes.
Sense Discrimination was made illegal.
The First Century of the Fleet
The first century of the Fleet was plagued by a number of issues:
Inequality - The fleet had a small elite of nobility and a large population of poorer people with fewer rights. Due to general mismanagement and issues with housing, people were miserable. Though the food production levels and population are mostly unchanged between then and now, mismanagement caused food to rot or go to waste, causing hunger.
Reproductive Demands - the general poor conditions and the despair of not being on a planet for multiple lifetimes was causing fewer people to choose to have kids. Rather than the 'carrot' method which would be used after the Century Rebellion, the nobility attempted to force reproduction through limiting birth control to those who haven't had children yet, limiting employment options for women, or outright demanding people have at least two children by the time they turned thirty or face legal consequences.
Sense Discrimination - those with daemons which had senses without human equivalents were forced to live in a few specific Halls set aside for their use and banned from leaving them. This includes echolocation, electroreception, empathy, and the ability to sense magnetic fields.
Artificial gravity was invented within the first century. It did not entirely replace the rotational system which had been used before, but some artificial gravity has been set up in such a way to remove some of the quirks that made rotating and planet gravity behave differently.
The Launch of the Fleet
The Fleet as a project was spearheaded by the country of Kanto, which was the most powerful and technologically advanced. They produced the four Great Ships. The 64 lesser ships were produced by other countries, though designed so that they could be docked.
The Dying of the World
The stars dotting the sky began to fade, and the sun and moon were becoming very slowly but measurably dimmer. Pokemon began dying out, smaller weaker species like Flabebe first.
They originally lived in the Dead World, in the wilderness. They avoided cities, for the most part, but travel was difficult between them due to Pokemon.
They were non-sapient.
History of the Dead World
Both the planet and the pocket dimension it was housed in were called Raisoth, though the name is rarely used on the Fleet.
The world was divided into about 200 countries with a number of different cultures.
Kanto and its neighbor Johto were the most powerful and influential countries in the world.
They were a bit more technologically advanced than Earth, but not by much.
The fleet was officially a "global project" and designed to house people from all countries. In practice, because Kanto was the wealthiest and the one responsible for building the ships, this wound up being tilted heavily towards people from that region. About 30% of the original refugees were from Kanto, 20% from neighboring Johto. Most of the rest were from a handful of their closest allies.
After 200 years / 8 generations on board the ships, what had started out as distinctive races have become very mixed. The fleet's housing system does not encourage separation of races or cultures the way that the housing system of real world America does, and race is a non-issue to a majority of people. Kanto/Johto genes are more common, though are also fairly recessive.
These spoilers are unlikely to be useful, given that there is literally no way of determining these events in-universe unless a Daevinity Demon or other arbitrarily powerful information dispensing magic is brought in from outside. As these events are tens of thousands of years in the past, they will not be relevant other than insofar as to explain the conditions of the universe.
Origin of the Dead World
The dead world was a research project from a large multi-universe civilization which had achieved post-scarcity and peace through combining the various magic systems in the universes it reached. Unfortunately, after a short while it became unanchored from the adjacency to the nearby universes and "fell" trillions of adjacencies away from its original location in the multiverse. There had been more than humans on the research team, originally, but humans had been the only ones with a large enough population to persist. This happened somewhere between 20,000 and 500,000 years ago, probably. Pokemon had begun as a few pets, which escaped. There had been no animals on the world, only plants.