'Murrica!
Technically the Big Bang created the universe. I don't think it wasn't directly related to the creation of the planet other than providing the space in which it was done. Now, the exact process in which the earth formed isn't something I remember terribly well, so you'll have to look that up yourself.
Technically the answer is aliens. Originally Earth was a government project, but stages were outsourced to dozens of private sector contractors. As a result, the whole thing was completed years off schedule, massively over budget, and largely without the features promised. As a result, the project has been shelved, forgotten and generally embarrassing to talk about.
This, incidentally, is the answer to the Fermi Paradox.
