Yes, but we have no idea what the probabilities are. We have no basis for saying "it is probable that Mars had life." If we found native life on Europa or some

Yes, but we have no idea what the probabilities are. We have no basis for saying "it is probable that Mars had life." If we found native life on Europa or something, that would change things completely. Independent life arising at least twice in the same solar system would make it clear that life is common. But a sample size of one, with the anthropic principle, leaves us no clue. Life might be common, or we might be unique.