Unfortunately that probably means the touch digitizer in your screen is defective/broken/disconnected. Not much you can do there but take it to a repair center for evaluation. The S-Pen cigitizer is separate hardware, which is why you can still use it with that.
You can try to boot up the phone in Safe Mode just to make sure that it's not an app that's causing the issue, and maybe do a factory reset, but like I said, not a lot you can do to diagnose that via software other than 'nope, it's not responding to touch'.