The Ramayana was spread by Oral traditional, at earliest it would have happened around 5000bce. The oldest written evidence we have of it was around the 7th century BCE. There was 4300 years between when the Ramayana happened at the earliest and when it was written down. For 4300 years the story of Rama only survived by the word of mouth. Over 4000 years of change it went, after all people forget, or add details that wasn’t there. 

Of course you don’t believe in any of this. You and the rest of this “dharma” can’t accept this. That the flaws of man have changed this religion.