Chris, I see no indication that we should regard this parable as history. If Jesus had claimed otherwise, then I’d have to rethink my assessment.
However, I have no choice but to regard Genesis 1-11 as history, because the rest of the Bible does. For example, Peter writes:
2 Peter 2:4-9 (NASB) For if God did not spare angels when they sinned, but cast them into hell and committed them to pits of darkness, reserved for judgment; and did not spare the ancient world, but preserved Noah, a preacher of righteousness, with seven others, when He brought a flood upon the world of the ungodly; and if He condemned the cities of Sodom and Gomorrah to destruction by reducing them to ashes, having made them an example to those who would live ungodly lives thereafter… then the Lord knows how to rescue the godly from temptation, and to keep the unrighteous under punishment for the day of judgment,
If these events hadn’t historically occurred and were instead allegories, we would have no recourse but to regard the future judgment as allegory.