What kinds of people did Petrarch plan to include in De viris illustribus?

In his work De viris illustribus, Petrarch originally intended to compile a series of biographies focusing exclusively on heroes from Roman history.1

However, he later modified the scope of the project to include famous men from all of history. This expansion was driven by his desire to emphasize the continuity between the ideals of the Old Testament, the Classical world, and Christianity, with the collection beginning with Adam.1