Quite certain, this is it. The one and only.
You're welcome to your view, but considering that there are more stars in the universe than all the grains of sand on Earth, and that most of those stars have multiple planets orbiting them, the chances of this one little rock being the sole location of life, is absolute zero.
I'm sure it was a shocking experience for isolated primitives who encountered modern humans for the first time. Their entire worldview was shattered in an instant. Up until that moment, they were quite convinced that their little tribes represented the sum total of humanity on the planet.