Android System problem - Unable to share files, do factory reset
Apps that can't be uninstalled are apps that come hardwired in the ROM of your Android device. These are typically vendor specific apps or the Google apps.

"Android System" is pretty crucial to your device, so it's weird it's even possible to uninstall it's updates. Every Android device as this, but normally it's not listed. You can see it pop up in your battery usage statistics however, which is totally normal.

To fix your problem you probably need those updates to be installed again, but I doubt that will be possible using the Google Play Store app update system.
You can check, but I doubt it'll be there.

Another possibility is by checking for system updates for your device. 
How you can do that depends on the tablet/os version etc, so I can't help there.
On my phone it's in the settings under "About my phone", which has an update check option.