After the Titanomachy ends, Zeus claims His throne as rightful King to the Deathless Ones. Humanity did not yet exist. While most Titans were locked away in Tartarus by Zeus, Prometheus and Epimetheus--who were brothers--had been either neutral or on the side of Zeus during the Titan War and were therefor given a task. Prometheus was given the task of creating man and Epimetheus was ordered go give good qualities to all creatures of earth. So did Prometheus and Epimetheus. Prometheus shaped man out of clay and Athena breathed life into him. Epimetheus spread swiftness, cunning, fur and wings but ran out of gifts when he came to man. Prometheus remedied the situation by allowing men to walk upright and gave them fire.
It soon became apparent that Prometheus loved man more than the Olympians. When Zeus decreed that man must give sacrifice to the Deathless Ones, Prometheus stood ready to aid humanity. He butchered an animal and divided it in to piles; the bones and fat formed one of them, the good meat wrapped in the hide of the animal, the other. Zeus vowed that he would abide by the choice He made now, and picked the tasty looking pile of bones. Zeus was angered but could not take back his vow. What he could take back, was the gift of fire, and this he did.
Mankind suffered greatly without fire and Prometheus traveled either to the sun or Olympus to reclaim fire for his beloved mankind. This, of course, angered Zeus even further and so he devised a plan. First, he imprisoned Prometheus. He ordered Hermes to tie Prometheus to a mountain and had a giant Eagle come every day to eat his liver. As an immortal, Prometheus' liver grew back over night so his torment was endless. Before Prometheus had been taken prisoner, however, he had told his brother Epimetheus never to accept a gift from Zeus, as Zeus' wrath would undoubtedly also extend to the mortal race He had created.
And Zeus, indeed, was not done with His punishment. After imprisoning Prometheus, Zeus assembled the Theoi. He told Hēphaistos to fashion a woman out of water and clay. Hēphaistos did and brought the statue before Zeus. Zeus then asked Aphrodite to bless the woman with a beauteous face and feminine whiles. He asked Athena to dress her modestly and give her the ability to weave and craft, Demeter taught her to tend the garden. From Apollon, she received the ability to make music and sing. All Gods gave her treacherous gifts, including Hera, who made her curious, and Hermes, who made her cunning and quick of the tongue. Then, Zeus named her Pandôra (Πανδωρα), All-Giving, and breathed life into her. He then bade Hermes to deliver her to Epimetheus, along with a vase (pithos) Pandôra was never allowed to open.
Epimetheus had been warned by Prometheus never to open or accept a gift from Zeus, but he laid eyes on Pandôra's beauty and fell in love too deeply to reject her. He took her into his home amongst men and wedded her right away. And Pandôra loved Epimetheus, because he was a good man and good husband. She worked tirelessly to please him and helped him keep the home. Yet, she found herself drawn to the pithos she was told never to open. Her eyes would wander to it constantly and Hera's gift eventually prevented her from holding to her promise.
On a day when Epimetheus was away from the home, Pandôra decided to risk a sneak peak at the contents she had fantasized about so often. She pulled the lid off of the pithos and out flew dark spirits of disease, death and the destruction of humanity. Pandôra hastened to seal the jar but managed to trap only Hope (Elpis)--by Zeus' decree or by mere accident.
Mankind was now plagued with illness, with failing crops, with all that make life hard. But they had Hope and soon, Pyrrha (Fire) was born to Epimetheus and Pandôra. Years later, when Zeus would flood the earth, Pyrrha and her husband Deukalion would survive and re-create the human race by throwing pebbles behind themselves as they walked; Deukalion would create the men and Pyrrha the women.
There are countless versions of this tale. It's featured heavily in Hesiod's Theogony and Works & Days but there seem to be older versions of the myth in which Pandôra was not made by Zeus but was an epithet of Demeter or Gaea who became a separate Deity. As such, Pandôra was a harvest Goddess, a Goddess risen from the earth to bestow gifts upon humanity. This would certainly seem closer to the meaning of her name; All-Giving.
The problem with the 'Pandôra's Box' myth as written above is in the inconsistencies. If Zeus wanted to punish mankind, why give them a beautiful woman? Why not drop the jar in front of some poor farmer and have him open it? Was there no curiosity in men at all? Why give Pandôra the ability to craft, sing and work diligently when she's there solely to punish mankind? If the pithos was a prison for the evils of the world, why was Hope locked in there as well? And if the pithos was, indeed, a prison, shouldn't we be without hope now? The same is true for a scenario in which there were actual gifts in the jar; why was Hope kept from humanity?
Scholars have tried valiantly to answer these questions but it doesn't become much clearer. There is a very old reference to pithos and Zeus in Hómēros' Illiad:
"There are two urns (pithoi) that stand on the door-sill of Zeus. They are unlike for the gifts they bestow: an urn of evils (kakoi), an urn of blessings (dôroi). If Zeus who delights in thunder mingles these and bestows them on man, he shifts, and moves now in evil, again in good fortune. But when Zeus bestows from the urn of sorrows, he makes a failure of man, and the evil hunger drives him over the shining earth, and he wanders resepected neither of gods nor mortals."
Could one of these have been given to Pandôra? And if so, which one? Was it the pithos holding the kakoi or the pithos holding the dôroi? Her name seems to indicate the latter, the myth the former. If it's the pithos holding the kakoi, why was hope in that jar? Shouldn't hope have been in the other jar? If it was the pithos holding the dôroi, why was it a good thing hope stayed behind? Don't we need hope? And if hope is a bad thing, why was it in the jar of blessings? Another possibility is that, when opening the jar, the blessings--because this theory works only if the pithos that was given to Pandora was a pithos of blessings--Pandôra caused mankind to lose the blessings Prometheus had bestowed upon them. All that was left, was hope.
Aeschylus, writer of a Hellenic tragedy dating back to C5th B.C. indicated that it was not Zeus, but Prometheus, who saved Hope from leaving the jar and, as Aeschylus explains it, our hearths:
Prometheus: Yes, I caused mortals to cease foreseeing their doom.
Chorus: Of what sort was the cure that you found for this affliction?
Prometheus: I caused blind hopes to dwell within their breasts.
Chorus: A great benefit was this you gave to mortals.
If this was the case, the jar would have, indeed, contained blessings which were lost upon opening of the jar. Prometheus kept hope alive for humanity, allowing us to weather the evils already in the world even now we had lost most of our ability to withstand it.
This idea is not as weird as it may sound; I spoke earlier of the Ages of Man. Every new age, we lost more gifts from the Gods because our gifts gave us hubris. Because this myth is set before the flood of Deukalion, it's set in the Bronze Age. Hesiod had this to say about the Bronze Age:
Zeus the Father made a third generation of mortal men, a brazen race, sprung from ash-trees, and it was in no way equal to the silver age, but was terrible and strong. They loved the lamentable works of Ares and deeds of violence; they ate no bread, but were hard of heart like adamant, fearful men. Great was their strength and unconquerable the arms which grew from their shoulders on their strong limbs. Their armour was of bronze, and their houses of bronze, and of bronze were their implements: there was no black iron. These were destroyed by their own hands and passed to the dank house of chill Hades, and left no name: terrible though they were, black Death seized them, and they left the bright light of the sun.
Parts of it come close to a world void of hope, full of evils and/or void of all goodness but hope. It was a bad age and the people who lived in it, destroyed themselves--perhaps due to whatever was in that pithos?--and remained forever nameless spirits. Of course, the creation myth part of this age doesn't fit the myth at all.
Perhaps, Pandôra was an invention of her time, following a shift in culture towards a patriarchal society. Perhaps, her myth got mangled when it came in contact with the story of Adam and Eve, which it resembles. It is said that the Theoi cannot impede on humanity's free will and so they created a creature with the will to do as they pleased. Quite a nice loop in that clause, huh? Whatever happened, I don't think Pandôra meant any harm. She was made to be a certain way, to reach a certain goal, and she did.
I don't think whatever Pandora unleashed, influences us of the Iron Age. With (nearly) every new Age, humanity was created anew, downgraded from our previous incarnations. Whatever Pandôra released was restored upon reaching the new Age, brought about by Pandôra's daughter Pyrrha and her husband Deukalion. That is, in my opinion, Pandôra's greatest gift; her daughter. A daughter who restored humanity and opened the way for the Heroic Age in which most epic tales of bravery are set.