I have often wondered with fascination how we have a temperature variation of 120*C from the polars to the tropics and of those temperatures their is a 50*C window that we can survive in and then a further 20*C window needed for survival on the scale we do. We are at a perfect distance from the sun (a sun that is the perfect size), we spin at the right speed and have a steady orbit. Our planet is the perfect size to have an atmosphere(unlike mars) and the atmosphere and planet work in tandem to keep a nice balance of gasses for us to survive in. Isn't it wonderful.
The Earth's axial tilt varies between 22.1 and 24.5 degrees. Although it takes approx. 41,000 yrs for the tilt to go from one extreme to the other.
Also, the Earth doesn't rotate perfectly, it actually wobbles as it spins. Think of a spinning top. As the spinning slows down, the top begins to wobble. The Earth does this exact same thing. This is called Precession and is caused by the gravitational forces of the sun and moon pulling against the Earth.