Arduino Interrupt example not working
I think you misunderstood this example: it is not expected to automatically blink!

The LED is suposed to change state at every change of level on pin 2. This supposes that you wired something (e.g. a push button) to pin 2 and that this will make pin 2 change level when something happens (e.g. you press the button or you release it).

On your diagram, there is nothing wired on pin 2, so what you observe is just normal.

If you want to see attachInterrupt in practice, then connect pin 2 to a button with the other button lead connected to GND.

Then you can observe what happens when you play with that button.