Explain why most interrupts are active low?

This answers why most signals are active low when you see the transistor level of a module, active low implies that the capacitor into the output terminal gets charged or discharged based onto low to high and high to low transition correspondingly. While it goes from high to low this depends onto the pull down resistor which pulls this down and this is relatively easy for the output capacitance to discharge quite than charging. Therefore people prefer using active low signals.