Inspirion 7506: Windows 11 Upgrade issue with keyboard & mouse

Hi. I am hoping someone can help with my issue. When Windows 11 first came out, I downloaded it onto my Inspiron 7506 2-in-1 laptop but immediately I noticed an issue: the keyboard & mousepad are not functioning as they should.

1. The shift keys barely work on the keypad, if at all. 

2. I cannot toggle between screens by using Alt+Tab.

3. I cannot highlight on screen text. Even when using the mousepad, keyboard (shift+home OR shift+arrow).

I figured that it was just a glitch and that Dell & Windows would sort it out. So today I downloaded Windows 11 again, as two years ago I reverted back to Windows 10. Big mistake. The same issues above are the exact same issues now. I am not a technology professional and have searched high and low to find a solution to no avail. Could someone please help me?