> What are the odds of being born a human and not a bacteria, a fly, or, apparently, a nematode?

If you're having that thought and expressing it on the internet ... 100% certainty.

In a similar many worlds conjecture, with an infinite number of potential universes with an infinite combination of fundemental physical constants, what are the odds that I'm here in this, one of the only possible universes with a sweet spot of values that allow life?

Observer bias is a thing.