The very simple Joomla contact form module is a bare bones module example to help developers with basic PHP skills get started creating contact forms.
The very simple joomla contact form module on github
It does not support some standard Joomla features, like internationalization and template overirdes, as this would make it more complicated than it needs to be, for a bare bones example. It is not intended to be an example of best practice.
Useful Joomla docs related to this...