The difference between improbable and impossible is vast, no matter what the number calculated actually turns out to be. Life could indeed be a highly unlikely event on the grand cosmic scale. That does not prevent it from happening, and more to the point: once it has happened the probability is irrelevant. You could flip 50 heads in a row the first time: probability does not say when in the course of events the improbable happens. To argue from the existence of life that the "improbability" of it is evidence of miraculous intervention is just a post hoc ergo proctor hoc logical fallacy.
Math is not evidence for reality. If you have a mathematical model that says something cannot happen when you have evidence around you that it has, the probability is high that the mathematical model is erroneous.
Translation:
Just because an event is improbable doesn't mean it's impossible. An event could be as improbable as you like but can still happen. In point of fact it has happened.
It's no evidence for special creation that the spontaneous generation of life is improbable.
And if a model says that an event cannot occur when it fact it has occurred, then obviously the model is wrong.
What is it that has occurred that has been claimed to be either improbable or impossible? The spontaneous generation of life.