According to Catholicism who were the mandated leader(s) of the Old Covenant?

Who do Catholics believe that God put in charge of Judaism in the Old Covenant? I assume they believe that there was someone in charge with continuity from the time of Moses to Christ and that they know who this was, or do they believe that it perhaps wasn't as cut and dried as in the New Covenant with the Papacy? I am a bit confused because I have heard a number of figures mentioned such as the Sanhedrin, judge (Dt. 17:9), priesthood, High Priest, etc. Two things to consider are that Moses was not a priest (not a Levitical one at any rate) and that presumably whoever Mt. 23:2 is talking about weren't priests either, although perhaps they sort of depended on the priests in some way.