Prompt-Inspired Elder Humanity

I am looking for a story where Humanity is a mysterious elder race: -Humanity is the most advance specie in the Galaxy/universe -Humanity as percusors:seeded life or were the first to develop space travel -Human technology: Humans have moved to another region of space or have ascendant and left their technology behind ala the Alteran from Stargate. -Humanity dissapeared: little is known about humanity expect it was advanced to ridiculous level. -Humanity is highly evolved: humanity is immortal ala elves from Lotr and is aloof to other life forms. And other species have to convince them to fight against an ancient evil. Or humanity have become psionics with off the charts powers. Or humanity has become a huge mind hive while maintaining their individualism (i.e drich's fanfiction: Perchance for dreams) but the majority have to agree in order to take large scale actions such as war.
The story doest not have to be from human perspective. The story can be fanfiction or book or online novel