And as life complexity increases, so does the the complexity of the processes that make it possible. Humans are the result of a huge number of individual, albeit not all independent, events, each with a very low probability. Multiplying those probabilities, as it's required when determining the probability of occurrence of a sequence of independent events, yields numbers that are hard to event write down without special notations.
As I see it, the only way out is to postulate evolution based on other non-probabilistic evidence, and then to conclude that in spite of the low probability those events still happened.