So, is this normal or am I just not aware of how inputs actually function?
Yes that is normal. You are seeing the effects of a 'floating input pin' condition. You don't even need to add a wire to see the effects, just do a continuous digitalRead() on an input pin with nothing connected to it and it will return 1 and 0 values randomly due to noise. That is why when wiring up to simple switch contacts one must utilize external pull-up or pull-down resistors (or enable the internal optional pull-up for the pin) so that when the button is not being pressed and it's contacts are open there is still a valid voltage (either ground or +5vdc through a resistor) seen by the input pin. An input pin with nothing wired to it is not presented with a valid input voltage to sense so it goes insane and just lies to you if you try and read it's value.
That make sense.