Great falsehoods

The cult of the eternal.

The cult of suffering.

The cult of struggle.

The idea of the just world.

Hardwork and productivity as moral duty

Stoicism and reenchantment.

I guess it depends how much you respect Cicero. He was a favourite of Deists and Atheists because A) his writing survived B) it said things they could use against the church and C) he had a good reputation.

The "superstitious" positions he decried were as much a part of classical paganism as his own (and arguably more immersed in the bubbling cauldron of the spiritual world, which becomes more alien and chaotic the deeper one descends, rather than the spirituality that is order seeking and touches lightly upon the gods for orientation, which stoic positions clearly encourage).

I guess it depends upon what you are looking for out of your spiritual path but I would say that the task of this generation of pagans is reenchantment, making the power of the gods tangible, and that will ultimately require going into the depths and bringing back new understandings, the job of ordering it will fall on those who come later.

Homer and spiritual liberation

We are lucky to have Homer's Iliad as our oldest text. In many religions their oldest book becomes the holy writ, if not unquestionable, then beyond all overturning on a societal scale.
 The flaws in the Iliad as a religious text have been seen clearly since at least the dawn of philosophy ( Xenophanes famous critique of anthropomorphic gods) though as a great humanist text, a tragic celebration of the human with all its flaws, it is top tier. These two aspects grant the west a unique and enduring legacy.
 Unlike early texts in other religions which through their authoritative vision obscure what came before them, the failure of Homer to provide unambiguous religious direction (a straight answer to the question 'how can a person be pious?' is sorely lacking in Homers cosmology of gods with competing demands) lifts back the veil on the true wellspring of religion, not as a book, but as the local cults of village, countryside and wilderness whose rituals engaged either a single deity or the relationship between a small number of gods at any one time.
 Adding to the ease with which seekers can step beyond the Iliad is its reactively compact focus, being a snippet of a larger narrative about the Trojan war, not beginning with a cosmogony of even the most oblique kind (such as the creation of Enkidu in the Epic of Gilgamesh) or primarily concerned with revealing religious truths (the Bhagavad Gita). Instead it is hemmed by material concerns, the outcome of the war, the scholarly quest to prove or disprove its veracity, find the sites of its action and date its description of landscape, on one side and human concerns, value, love, virtue, status, honour and the tragic, on the other.
 The humanist aspect, the approach towards its characters, both protagonists and antagonists, as both heroic and flawed, with a complexity lacking in equivalent texts, derives partly from this compact focus, its cast remaining consistent throughout the story. This is a tale of human desires and the Homeric hero is the individual who tests their will against all outside influences, whether those influences are the good of society, conventional morality, other wilful creatures, nature, or the gods themselves. This licence, granted by our oldest text, is a call to human freedom, with all the attendant triumphs and catastrophes, both for the hero and all that surrounds them.
 It militates against religious strictures while at the same time time admitting a world alive with gods. In it humans are contacted, opposed and killed by the gods, rail against and are subjected to fate and destiny, it speaks of the world we inhabit and the possibilities in being human in such a world, but little about how a relationship with the gods is to be built and maintained (or what is offered is contradicted by the heroic imperative). Its failures as a holy book do more to reinforce its message of human agency than any explicit commandment ever could, forcing seeking individuals to look beyond it into the spiritual milieu from which it drew as well as to the multitude of texts that succeeded it to learn methods of how to petition the favour of and divine the will of the gods, rather than claiming to have bottled their essence, dead and immutable on the page, dictating to humanity without any reference to world in which the gods are to be experienced.

On myths

Myths have a certain truth value (none also being a value) and a lot of it depends upon the ontological stance you take while reading them.

The mythic is measured against the human, and as long as we are the kind of creatures we are there will be certain myths that always have an application, so it's not so much a question of myths becoming outdated as their meaning changing based on the zeitgeist their interpreter occupies.