The upstream-facing port of a USB hub, as shown in your diagram, must connect to a host or a downstream-facing port of another hub.
If you want your MCU to also be able to communicate with a USB device (camera, drive, mouse, etc.), it will need to be able to function as a host and thus will need be an OTG device.
A USB HID-class device can send data to the host in response to received control requests (Get Input Report, Get Feature Report) on the control endpoint or in response to received IN token packets on the interrupt IN endpoint. The device cannot send control requests.