Someone asked me the same question! I just know that popes pick their names to indicate what their priorities are. Francis picked a totally new name. I think that in itself signals a time of change in the church, we can also look to st Francis And the traditional association with kindness, mercy, not to mention his "Rule" (basically that Christ had no possessions).

Typically the previous pope with that name is where you look. Maybe the first too. Leo I stood up to Atilla the Hun. Leo XIII championed trade unions and workers rights (though also rejected socialism). Make of it what you will.