Earth's Core Was Created to Protect Life

Our planet was created for life.

A smaller planet, like Mars, would be unable to hold our atmosphere, which protects use from meteoroids and keeps the temperature within the range needed for life.

A larger planet, like Neptune, would trap too much atmosphere. The pressure and temperature would greatly increase.  A  stronger gravity from the increased size would also trap harmful gases in the atmosphere.

Earth has a strong magnetic field. This protects us from harmful radiation from the sun.