Nibiru is a brown dwarf is orbits the Sun every 3700 earth years but it has a elongated elliptical orbit so it is only observed when it is near the sun which is very rare. just a few days every 3700 years.
A brown dwarf is between a star like the Sun which is a Yellow dwarf and a gas giant like Jupiter, indeed it is thought that the gas giants use to be red or brown dwarfs
A long time ago the ancient Earth was in a orbit further from the sun then it is now. when Nibiru passed through the solar system it knocked Earth nearer to the sun. that is why earth has liquid water on it. if it was where it is now the water would have evaporated in the early days when the sun was hotter.
According to ancient Sumerian mythology people from the planet Annunaki genetically engineered apes to use as slaves. These were early humans.
Annunaki is part of Nibiru's solar system of 7 planets, as a planet on its own would be too cold to support life when it is in the outer reaches of its elliptical orbit.
The Star of Bethlehem may have been Nibiru and the Angel that impregnated Mary might have been from Annunaki as the year 0 is thought to be the last time Nibiru was observed from earth indeed the 3 wise men could have been astronomies. so Jesus may have been a human /annunakian hybrid. But I am not getting into a religious debate on this I leave it to you to decide.
The next time Nibiru passes through the inner solar system will be in the year 3700 which is the year Nostradamus predicted the end of the world.