BTW did have installed some older openSUSE (or even another Linux distribution) before installing Leap 15.0? Did it work? Maybe you could try using a different USB keyboard and see if that's rather a keyboard or an USB controller issue. Or you could try attaching two keyboards and use commands "lsusb" (or "lsusb -v") and "hwinfo --keyboard" to check if both keyboards are detected properly. And try both with and without the USB hub.