The common peoples language of the Buddha's time probably had a lot of similarities to what we know as Pali today, however the Pali of the scriptures dates from about 500 years later, and we really have no idea what if any changes occurred in the language from when the Buddha spoke it, to when it was recorded centuries later. We can be pretty sure the language didn't have an alphabet, ie was not a written language, until, in moving to other regions, pali adopted the alphabet of that regions written language, or fairly similar.
18 years ago I made one of the most important decisions of my life and entered a local Cambodian Buddhist Temple as a temple boy and, for only 3 weeks, an actual Therevada Buddhist monk. I am not a scholar, great meditator, or authority on Buddhism, but Buddhism is something I love from the Bottom of my heart. It has taught me sobriety, morality, peace, and very importantly that my suffering is optional, and doesn't have to run my life. I hope to give back what little I can to the Buddhist community that has so generously given me so much, sincerely former monk John