Eve as an archetype of womanly vice
This idea is highly controversial, historically speaking, but it was not controversial whatsoever during Boccaccio's day. The popular belief was that since Eve sinned by allowing her desire to overwhelm her senses, and by sabotaging her marriage with deception, that she ruined human history. That's not exactly what the Bible says of course, but people in the past believed that, and Boccaccio mentions her in that light, remembering her willingness to be deceived as an essentially female vice.
The ontology of Isis's legend
The argument from Egyptian folklore is that Isis earned her divinization as a superb queen and sovereign in Egypt. Her folkloric divinization is similar in kind to the Pharaohs who were similarly honored. The existence of Isis's legend is tangible evidence that, although most Europeans would have never dreamed of a woman attaining the same height of a male leader, there are cultures who have a different idea of gender. By the way, Isis's story is interesting because the story became popular in Greek folklore too.
Medusa, a symbolic archetype
Another mythic connection between women and snakes is illustrated in Boccaccio's retelling of Medusa's story. By mentioning her, he invokes her mythic symbolism. If one snake makes Eve's story into a darker one (to say the least), then a head full of snakes is a kind of ultimatum. Medusa is the ultimate depiction of the effect a woman can have on others. Medusa literally petrifies her victims, which can be seen as the opposite of encouragement or nourishment, which are typically regarded as motherly aspects. She is an anti-mother, and she loves her snakes as herself, but not others.
Dido, or Elissa
Dido is the primordial queen of Carthage who was an influential character in Roman mythology, especially Virgil's Aeneid. Just like mythic Romulus and Remus, the founders of Rome, Dido also receives a kind of divine call to the city of Carthage which she founds and rules over. From a mythic perspective, Dido represents female competence. She is very often regarded as a friend and confidante by her contemporaries, very much like Sheba in the Abrahamic stories of the Bible.
The motif of women heroes
The most important symbolism in the work is the central one: that women are obviously heroes too, and although their heroism sometimes differs from their male counterparts, often it doesn't differ. For instance, women are divinized among these myths. There are instances of dozens and dozens of queens, good and bad, and there are ample mythic examples of the instinctual power and prowess of women in leadership roles, so the motif is simply a forceful reminder that in terms of leadership and power, women literally can do what men do, and have done it many times.
