But I still don't understand why a transmission issue has you doubting the intent of the author?
The transmission doesn't have me doubting the author's intent; I think it clarifies how we should understand his intent.
How does that argument come together. If timelines were part of the original writings, and then some scribe made a mistake thousands of years later and some copies got corrupted, how does this make you doubt the original author's intent?
I don't think this was a scribal mistake. A mistake implies that it wasn't done on purpose and with intent. I think the differences were done on purpose.
There is a lot of agreement between the LXX and MT. Both record chronological genealogies that state the father's age at the time of the son's birth. All manuscripts agree there. The differing numbers may give us reason to question the timeline within a few hundred years, but nothing beyond that.
The chronology in the MT, LXX and SP differ by several thousand years, not several hundred. The difference is not insignificant. It's not a copyist sort of error; the differences seem to be systematic. There is something else going on besides a simple mistake or two by some scribes.
But the idea that one scribe made a mistake some ages later, therefore we're going to turn the book of Genesis into a metaphor? How could this possibly make sense to you?
I don't think the genealogies are best classified as metaphor. They are probably best classified as Ancient Near Eastern Genealogies. ANE Genealogies weren't usually reporting bland facts for the sake of reporting facts. Genealogies were often used to justify something or provide meaning and significance to important events. The Sumerian King list is a good example where the list isn't just giving the reader some dates; rather it's trying to justify a particular ruler/dynasty in the list. Genealogies were used to establish ancestors, which was important for things like land claims, kingship, dynasties, wealth, prestige, etc.. Israel's genealogies weren't all that different except they were used to emphasize the importance of God with His people; so important events like the Exodus, the Temples, etc.. happen on significant dates. In this way, Israel's claims to land and election by God are emphasized by the use of a schematized genealogy.
For example, in the MT, the Exodus occurs 2/3rd's of the way through a 4000 year era. The year 3999 of this chronology just coincidentally happens to be the year the Maccabees re-dedicate the Temple. The implication seems to be that the Maccabees re-dedication of the Temple corresponds to the Exodus as it begins a new era/new Exodus in the year 4000.
It's also the case in the MT that the time from the entry into Egypt to the Exodus is 430 years. The time from the Exodus to the 1st Temple is 480 years. But if we allow 40 years from the wilderness wanders and 10 years for the conquest, then it's 430 years from the time Israel takes Canaan to the 1st Temple. It's also 430 years from the 1st Temple foundation to it's destruction. It's seems obviously highly schematic that the MT divides Israel's history into 430 year periods. There seems to be clear emphasis on the Exodus, 1st Temple, and 2nd Temple.
This doesn't seem surprising or anything. The LXX and SP do the same sort of thing with the significant events in Israel's history except their chronologies are different. It seems clear that the the genealogies should not be read as literal if we are trying to get the author's intent. Rather, they should be read in the context of ANE Genealogies where the theologically significant events in the history of Israel are emphasized by using a highly schematic chronology. The purpose is probably to lay claim to Israel's election by God and land grant by God.
