Why did my pushbutton LED circuit work when my wiring was wrong?
The LED wired to the push button was turned ON by the push button closing the circuit, without any intervention from the micro controller.
That's a pretty simple circuit: a voltage source, a switch, an LED and a resistor, all in series. When you close the circuit the LED turns on. Simple.

The code on your microcontroller is watching the state change on the button and turning ON/OFF the on board LED: it has nothing to do with the LED in your circuit/breadboard.