Everyone is born with a system. Well technically, they just needs to unlock it. Sounds simple right? But not really. The system a human unlocks can be anything. Someone can unlock their blacksmith system just by walking by a forge where others need to create their very first weapon before it unlocks. Some people unlock a masters system that will take them to soaring heights that allow them to learn mastery skills. Others unlock unique systems such as magical smith which is the same as a blacksmith but they can create magical items. The only catch is that if a human hasn't run in to the proper conditions to unlock their system by the age of fifteen then that's it, it's all over. Their potential to unlock a system is gone and they become an average human with no potential to level up and grow. They fall to the lowest class lucky even to make twenty gold a day when bread could cost a whole one of those.
Now it may be a rare case but for Walker, it's becoming a closer and closer reality, Walker Will turn fifteen tomorrow. Well more specifically in 13 hours or at least that's what's left on the system countdown every human gets until they either unlock or lose their system. See his father Garret has a unique system. It's not as good as a master but he has an Elite Guard System. This helps him patrol the capital city Diamond, its in the Crystal kingdom named for the first ever King Roman Crystal many years ago. Thanks to his father's job Walker has been able to meet many various people in a day, giving more than enough chances to try unlocking his system.
The world has uncountable types of systems some even spanning to other worlds or universes. But here there are a few notable races that call systems a blessing of the world. The elves of the forests pride nature and magic. The dwarves of the mountains hide away only caring for crafting and mining. Demi humans are tied to their distinguishing features unlocking related systems. Demons hold more nefarious destructive magic powers often causing trouble with any system. Ancient dragon like monsters have systems related to their species, often leveling and becoming much stronger more easily. Angels, Merfolk, and other various species scattered through the world have their own challenges and strengths.
The only thing that's certain is that when it comes to systems, you either do anything and everything you can to unlock it or you lose the chance forever.