There were many works similar to the God Slayer anime, such as Ghost Blade, Sword God Realm, Attack of the Giant, Gate of the Fate Stone, Tokyo Ghoul, and so on. These works had unique storylines and characters that were deeply loved by anime lovers.
One common theme is heroism. The dragon slayer is often seen as a hero, brave enough to face a powerful and dangerous foe. Another theme is coming - of - age. In many such novels, the protagonist starts as a young or inexperienced person and through the act of slaying the dragon, they grow and mature. For example, in 'Eragon', Eragon goes from a simple farm boy to a powerful dragon rider.
In fanfiction, dragon slayer magic might be outlawed to create more interesting plot twists. For example, it could make the protagonist's journey more difficult as they have to find alternative ways to deal with threats. It also adds a sense of danger and mystery. If everyone could use dragon slayer magic freely, the story might become too predictable.
The Demon Slayer anime is largely based on the manga, but there are inevitable adaptations. Some character expressions and fight sequences might be slightly different to enhance the visual impact in the anime.
It depends on personal preferences. Some people think the manga has more depth and detail, while others enjoy the animation and voice acting of the anime.
In general, the Demon Slayer anime is very faithful to the manga. Some minor changes are made to make the animation more fluid and engaging, but they don't change the core of the story or characters.
The Demon Slayer anime has adapted a good chunk of the manga. But keep in mind that the manga is quite extensive, and the anime might take some time to catch up completely. Also, sometimes the anime might make some changes or omissions to fit the medium.