You'll never know that value with any certainty as there may be multiple ways life could emerge from non-life on Earth (not just one) and ways it could emerge on other worlds that we could not know.

This is an equally excellent argument that aliens speak English.

If the universe is large enough, with enough inhabited planets, it's very likely some alien, somewhere, speaks perfect English.

At the same time, it's extremely likely we never encounter them.

For very large values of large enough that is always true. Even on the condition that they use the Latin alphabet and have exactly the same set of words and exactly the same set of meanings of words, there are still n factorial ways of assigning a meaning to each word. For n=1000 words that is already gigantic. Even if there is a civilisation that speaks English words on every planet in the observable universe, the probability that any one of them assigns the same meaning to words practically zero.