Z-wave or wifi

I recently set up a new system that include the base station, motion detectors, cameras, door sensors and a range extender. My understanding was that the various devices would communicate with the base station via Z-Wave, but my router shows them as being connected to my wifi network. Is this usual?I also have the Ring security system integrated with Alexa if that has any bearing. I understand that Alex and the base station communicate over wifi, but not the component devices. Any assistance would be greatly appreciated.