The fact that there are multiple "religions" including some material from Mithraism, most Sumerian mythology, Egyptian mythology, and especially Vedic and Eastern mythology, that directly, without allegory, speak about beings from outer space arriving on Earth and guiding humanity.
They describe these teachers in the same way, the symbolism associated with them has evolved, adapted and been carried to many areas while still keeping the core of the message, and leading vastly different civilizations to be guided by very similar spiritual principles.
All of these also agree on and explain a narrative of migration of these beings, as these "Aryan" (noble) advanced non-Earthly beings made long movements eastward and westward.
It must also be noted that this migration was very natural, resulted in zero major conflicts or genocides in what modern history calls "prehistory" and created a chain of events so well organized that it had to be external influence.
It also speaks about their departure in all too similar fashion.
This is also barely 5% of the evidence we would have had abrahamic influence not ruined most of our writings and cut us off from spiritual vision.
The idea that we were guided and made for a purpose by beings who did the exact things mentioned above, whose actions are well documented, and whose existence can both be logically believable as well as able to be experienced, was literally common sense in ancient times, and absolute truth in "prehistory", which was actually a spiritual Golden Age.
If people are completely dismissive even after this explanation, they are a symptom of the disease that is anti-Gods programming within society. Rest assured, that mess will be cleaned up.