You were undefined. The set of conditions for producing sentient mammals was not included automatically at the time of the BB owing to the fact that there was nothing inherent in matter and energy at that time that had to lead to you. Since you missed my subtle link to Anderson's
More Is Different, here is a quote from a
follow-up to that,
More Really Is Different:
Basically, significant time had to pass before 'you' could even be a subject of speculation, assuming some timeless observer who cared about such things. The probability of humans was undefined for a long time, since the 'construction' from elementary particles to the cosmos today is several scales and orders of complexity beyond starting conditions. It would only make sense to speculate about a 'you' at least starting with the existence of the human species.
I imagine a super-determinist (SD) would not agree; i.e., that all uncertainty owes to a near infinity of causes/influences to any event, the bulk of which are vanishingly small in effect and so usually ignored. In that case, an SD might agree, assuming he/she had existed somehow close to the time of the BB, that he/she could crank the numbers and assign some value to p(you).
But that lonely SD would have to assign extremely small probabilities to all things, given that the sensitivity to exact conditions leads to differing outcomes for same processes or events. The probability of 'crap happening' is p=1, but the likelihood of any specific outcome is small. That is true for all things, and is trivial, not profound.