That question touches so many different realms that are unknown it staggers the imagination (which is why I like Roger's quote so much) and the allegories you provide all rely on external actors.
If it were like a computer (digital), who built the computer?
If it were like a chemical reaction, what physical action caused the chemicals to combine?
Biological might be a better tack as it's a weird mix of the 2 above and is the entire reason we're here to question its existence.
Big bang never made sense since if everything came from an initial explosion as white hot "debris", where did anything biological come from as (at least from our present understanding) nothing biological can survive on molten rock.
Water is another good one that doesn't do molten well.