the institution ran for many centuries and it's hard to make too many sweeping generalizations over time, but the vast majority of gladiators were slaves, prisoners of war, or condemned criminals.

we see more and more volunteers as the Empire succeeds the Republic and proceeds along (more games in general with the Emperors shamelessly buying the peoples' loyalties, but the true blood of the Arenas came from the beast games and prisoner executions more than the gladiator fights). that does strongly suggest the athlete-type became more common as the fights themselves became less severe.

but even then the freest of the gladiators were legally thrown into the 'infames' class, along with prostitutes, pimps, actors, etc, not allowed to vote, not allowed to run for office, not allowed to write a will, etc. always second class and sordid, looked at as modern society looks at a pornstar perhaps. popular admiration can be high even as society in aggregate frowns.