Ross Perot might have made Clinton known, but Clinton still got the nomination over other better-known candidates. Ross Perot only mattered once Clinton was the nominee. Within Democratic circles it was a "who can beat Bush and Perot" thing.
The Democrats ran a relatively weak field in 1992. A lot of the bigger names (e.g. Mario Cuomo) stayed out of the race, because at the time the decision had to be made whether to run or not, President Bush had sky-high approval ratings. At that point in time, trying for the Democratic nomination was considered a suicide mission.