SLOW PROGRESS

Long journeys themselves come with their own set of hurdles -- trade routes are much more taxing to overcome and more resources have to be prepared and used up just for travel. Additionally, difficult travel also results in less information being exchanged between different settlements, thus stunting technological progress -- where before two cultures could exchange information and invent new machinery, on Aathos people are more isolated from each other unless they've settled close to each other. This, on top of later complacency with being governed by Deities and belief humanity doesn't need to advance because they've got everything they need, resulted in a significant stagnation in technological advancements in every part of the world. Compared to Earth, Aathos would need centuries more to progress past each historical era, and those added up -- here on Earth, Modern Era started in the 20th century. In Aathos, same era would start as late as year 5000.

FOLKLORE OR REALITY

The main difference between Aathos and Earth, however, is the fact Aathos is influenced by forces outside of human understanding - belief. If enough humans believe in something's existence - such as cryptids, mythological creatures, or Deities - they might just come to life. This property, however, relies on belief staying as belief -- you have to truly believe something exists, even without concrete evidence, as the moment you have proof you don't have to believe anymore - you just take it as fact. And that results in the supernatural disappearing, leaving no trace behind.

FOLKLORE, MYTHOLOGY, CRYPTIDS

Due to the popularity of folklore and stories as a way to pass down knowledge and life lessons onto the next generation [or simply using mythical creatures to tell compelling stories!], it was only natural it gave rise to supernatural creatures appearing all over the globe, in every culture. From bigfoot and nessie, Rusalka and Baba Yaga, all the way to the pegasus and medusa, all could become real. Not all do, however, as more obscure tales or simply creatures who interact with the human world too noticeably cannot become real. This is due to the fact that too much interaction leads to humans accepting the myth as reality, killing the belief and causing the creature in question to simply phase out of existence - the individual or their whole kind - leaving no evidence of their existence behind.

One thing to note is that the mythical beings are not sentient and should not be considered human. They follow a set pattern of behaviours based on people's perception of how they will act and what they will do. With this in mind, they are closer to an AI than a human.

As an example: Imagine one local makes a fairytale about a water spirit living in the nearby lake who lures men into the water and drowns them, and spreads the story around the nearby villages in hopes to warn men to warn them against turbulent waters and drowning. If enough people believe the spirit is truly real, it will become so. If the story spreads, more water spirits could appear in other lakes [depending on where groups of believers live], or the original creature could get stronger. If, however, too many people try meeting the spirit -- too many eye witnesses, too many men bearing claw marks after almost drowning -- it will simply disappear. Additionally, if killed, not even bones will be left behind.

Another example would be the Greek Pantheon -- the majority of the myths would be made-up, but eventually a few encounters with the now-real deities would pop up. Still, these would be very sparse, simple interactions mimicking what has already been told - in fact, the main gods would be the rarest find given the interaction limitations. Spotting satyrs or a minor god would be more common in comparison, but still very rare.

HIGHER BEINGS - GODS

It is unknown what are the conditions for a myth to become reality - two tales could have the same popularity and belief and yet it's not guaranteed for both to come true. Similiarly, devoutly worshipping an already existing being doesn't elevate it to the status of a God either, not without a mass scale and influence from beyond. A God is created by human prayers - a primitive plea for safety and a full stomach, or a muse to bring inspiration - and a lot of them. They are not physical, being simple wishes and words, but yet they clump together, and if enough group together in one place, something might just answer them.

When the conditions are right, a consciousness is created, flotating in the space between, unaware of it's own existence and simply mindlessly observing the humans that pass through. As belief in the Deity grows, it's power does too until one day the consciousness realizes that it too, like all the people and animals and bugs and plants, is alive. They then usually take form of the last person they have seen but made invisible, or appear as an incorporeal spirit or the wind. Unable to interact with the world in any way, they are left to wander the world in order to familiarize themselves with their surroundings -- learning how humans act, what they do, how the sun is replaced by the moon at night. Slowly, they regain power: accidentally touching a flower turns into full control of their invisibility, changing their physical form letting them blend in, and slowly understanding speech and complex ideas as if waking up from a deep slumber.

They slowly become familiarized with their own "purpose" - or lack thereof - and try to find their place in the world. A Deity is made to help their people and to lead people, they know it deep down, somehow, even though they themselves haven't learned yet. They just know they cannot reveal their Godly status at any cost, else tragedy befalls them. They simply know, and that knowledge was always there from the moment they were "born", but simply forgotten like a childhood memory. They know they are bound by the universe's own rules.