Have you ever heard of the Miller-Urey experiment or any of the subsequent experiments which followed in fashion?
A primitive atmosphere of molecules such as ammonia, hydrogen, water and methane were subjected to currents of electrons, the molecules reacted over time and were examined to be amino acids and other simple biological molecules.such as lipids and carbohydrates. In 2007 the sealed flask was shown to contain over 20 amino acids.
Futher experiments used conditions such as those in deep-sea vents and volcanos. These experiments yielded similar results; 22 amino acids, 5 amines and hydroxylated molecules.
You mention probability. Yes, it is very unlikely in one instance that life would form, however if this was happening for millions of years all over the hot springs, deep-sea vents or in areas of high thunderstorms the probability suddenly becomes very high.
The probability of me winning the lottery is so small, however if I buy 10 million tickets it suddenly increases by 10,000,000 times that I could win.
Small steps to make life. Not just throwing all the compounds of life together and expecting an organism to form.