Assess please the originality of Calvin’s ecclesiology.
This is an excellent question. Here are some points to consider.
First, Calvin broke away from the Catholic church. In other words, the Protestant Reformation was a protest against the prevailing church of Rome. For this reason alone, we can say that Calvin and the other Reformers were original in some sense.
Second, Calvin rejected the seven sacraments of the Catholic church and only espoused two of them - baptism and the Lord's supper. This, too, was something new.
Third, Calvin reinterpreted the Lord's Supper. He no longer believed in transubstantiation. Instead be believed in the spiritual presence of Christ in the elements, which was a breech with the Catholic church.
In light of these points, we can say that Calvin's view of the church was in some way original.