Charlie, you think you chanced upon a gold mine that no one heard of? We all know good and well how to take Divrei Aggada. We are taught this at a very young age. The difference is that we know when this applies.
Actually, Seder Olam is in fact history. That is its function and purpose. That is what the Gemara quotes it for. It has also been pointed out here that the Pesukim show the 70 year span as well.
Even in those times they didn’t know how to count the 70. We count it from the Churban, but the conquest of Bavel started long before.
We are the ones with actual info. Everything else is putting together a picture from scraps. If you were to enter my house and do research you would no doubt draw conclusions different than the truth. Speculation would tell you that a waving flag shows the moon landing to be a fake. Knowing the truth tells you that it was folded.