Yes, you can record just your screen, without your camera or a face cam. Turn your camera off before you start recording.
You can turn off your camera before starting a recording by clicking the camera icon next to your camera device name (e.g. "FaceTime HD Camera") in the bottom left corner. This will turn off your camera feed during the recording.
You can also open the camera dropdown and choose No camera.
⚠️ Note: The camera cannot be turned off once a recording is in progress. Make sure to turn it off before you hit Record.