hey, nah you're not dumb! it's a super common thing with those compact keyboards. usually on a surface type cover, you need to use the function (Fn) key combo. try fn + delete (del) that should act as the insert key. works on most of those smaller boards. hope that helps!
To use the Insert key on a Surface Pro Type Cover, press the Fn + Delete keys simultaneously. Since the keyboard is compact, Microsoft hides this function. If you need it frequently, you can also use the On-Screen Keyboard or remap a different key using PowerToys.