If the existence of your personal consciousness — your SELF — does require the joining of a specific sperm cell and specific ovum, and you can have only one finite life at most, the probability that you would ever exist is virtually zero — here’s part of why
First, your Mom and Dad had to live at the same time, at some point near each other, produce the right sperm cell and ovum at the same time, have intercourse at the right time and do all the right ‘dance’ moves that time
And while your Mom probably produced only about 500 ova in her lifetime, your Dad probably produced about a sextilion sperm cells
And then, all your hundred thousands of human grand parent pairs had to do the same things!!!
And then, there’s your non-human grand-parent pairs — and the Big Bang…
The number of specific events that had to occur in order for you to occur may not be infinite, but neither is it countable
What’s more, there’s the UNLIKLIHOOD that NOW would coincide with all that
In other words, there’s no way in hell that your existence is the result of the combination of a particular sperm cell and ovum