First idea

Ok so the first one here has to be this one:

In a world where half of the continents are destroyed and taken over by monsters, people and monsters are evolving in a never ending battle for superiority. Monsters have gone for the majority evolution path (That there are just so damn many of them they overwelm humans) and humans have focused on power.(First military weapons and bombs) Modern weapons were useful against the monsters for a while, but of course the monsters evolved to be bulletproof and now have hard skins that bombs struggle to inflict pain on. Recently, a few individuals have gained mesterious magic like powers that use elements around them to fight. Along with these powers, weapons that can inflict huge amounts of damage also started appearing made of a special type of ore.

Ok now that the storybuilding is done... on to the main character:

Our mc is a creature of thousands of years prior that was in slumber to gift it's overflowing magic energy to it's subordinates and after the destruction of their clan or sect, our mc was left stranded in the long lasting sleep. While thousands of years passed, our mc's magic energy leaked into the surroundings like stone and dirt and it formed the material the humans only recently discovered. After the humans dug there to use the weapons, they finally woke our mc up and the mc discovered that a grave mistake was made somewhere long ago to land them in this situation.

Cool, now on to the actual damn story!:

After waking up, our mc observes the humans in it's natural state.(I was thinking something like a bird with very long and flowy wings and an extra long tail that usually hangs down, but is super sharp, but feel free to change!) It decides to intigrate itself in society to gain information on what happened to it's sect or clan and subordinates. It observes that to gain many advantages it will have to pose as a young girl around eighteen years old, but for more advantages on the battlefield it will need to be a boy and the younger the more time it has to investigate before someone realizes it's been alive for too long. The society knows about the monsters and the powerd up people, but need a licence to cross over the barrier that seperates them from the last line of defence. You do a basic test to test your mentality, strength and tactics before you can get a licence and if you have gotten enough accomplishments, you can rank up to the more elite who get treated better and paid more. So our mc works at a cafe as a eighteen year old girl in the day and fights monsters as an eight year old boy by night. It wants to reach the elite warriors to gain information, because without status no one will share important info and if you are at the top, you can find people that know what's going on.

And so our mc flies up the ranks as an eight year old and astounds everyone. I was thinking about how arrogant the elite always are, but it will be tricky being arrogant when how powerful you are doesn't decide everything and just because you are strong doesn't mean you are treated better instantly. Of course people scouting for talent will support those people, but they will have to bear with being on the same level as hardworking people.

The rest is up to you and I really hope someone writes or uses this.