Please do show me the math and arrive at a probability.
Sure.
10^57 isotopes of the various elements are in the solar system.
10^52 are heavy ions (greater than 1 supernova-explode-eject-transport-get absorbed in second star-that one explodes in a supernova-ejects isotope to interstellar volume-transports new isotopes-gets absorbed-by-third-star ...)
So, to get the material here you need 10^52 individual unique atoms created.
In less than 9 billion years between the Big Bang and formation of the earth.
9 billion years isn’t enough time to transport the material from star to star to star given the distances we know we have between today’s stars.
Worse. The earth is credibly 4.5 billion years old. (I have fossils 3.5 billion years old on my shelf.) 13.7 billion - 4.5 billion years = 290x10^15 seconds.
You require more than 10^30 reactions per second every second between the Big Bang and formation of the earth just to make the elements existing here on earth.
Ignoring the rest of the entire galaxies.
Assuming no travel time at all between subsequent stars.
Or you can believe in one miracle.
That is an absurd request, given the scope of the problem. Nevertheless, the answer can be approximated to a degree that dismissing it is itself absurd.
First, let's understand the problem. Any organism is, by definition, a Von Neumann machine.
A simple internet search on the problem of creating a Von Neumann machine will demonstrate more math than you could ask for, or I care to reproduce here.