Correct. All texts and phone call data is not readily available to view (You may be able to see the files if you select to 'unhide' system files on a PC, but the contents are not machine-readable without the encryption key).
If you can't unlock the device because the screen is non-responsive, unfortunately you cannot do any sort of USB control/debugging for obvious security reasons.
At this point your only option is to try the HDMI+Mouse 'hub' (again, not sure if this device supports video output or not) so you can see the screen on a TV and unlock using the mouse to emulate touch input, or to get the screen replaced.