A far more boring answer is: we don't know, and there are good reasons for thinking that we will never be able to know.
Historical linguistics has allowed us to reconstruct common ancestor languages of existing languages. Using written records of extinct languages, such as Latin and Sanskrit, we can robustly reconstruct ancestor languages up to around ten thousand years back.
This is especially true for language families, for which we have extensive historical written records, such as for the Indo-European language family, which includes Latin and Greek.
Beyond that, partly because language change is somewhat unpredictable over longer times, most linguists agree that there simply isn't enough information available. Because the earliest written records reach only about five thousand years back, this is never likely to change, either.
A few linguists disagree and claim to have reconstructed what is often called 'Proto-world', based on statistical analyses, but the foundations for this approach appear rather shaky.