Early civilizations developed stories to explain and answer questions the had concerning their reason for existence. In the Jewish Tradition, stories were handed down verbally for many generation before they were recorded in writing.

There were even older developed civilizations but there is no written or documented history that would tell you a name of the first “man”

(I am sure I will get some negative responses from radical fundamentalist Christians.)

As far as names go, we had evolved into something similar to our current state long before we had language and names.

and was quickly eaten by a dinosaur

If Religiously biased, you will want the name that is mentioned in your sacred book.

if a Scientist, you will believe that the name is not known.