What was the first person to speak?

It is likely that Homo erectus was the first to speak. Early erectus didn't seem to have much enervation to the tongue or lungs.

Adam if you believe the Bible in the most literal sense. But I'm guessing that's not what you're asking for.

The oldest language we know of is a theoretical reconstructed language called protoIndoeuropean (PIE). That was probably spoken in the Pontic Steppe north of the Black Sea by the Kurgan culture some 3-4 thousand years before the common era.

Older than that, a language we can only imagine, is Proto-World. That was probably spoken by our earliest ancestors in Africa some 50,000 years ago.

Not you, apparently.

Just kidding. What do you define as speech? Lots of animals "speak" to one another, though only humans have language. Homo sapiens have had language as long as they've been around (capable of it, anyways). Before that, I wouldn't be surprised if there were a number of pre-homo sapien species that developed languages.