"Why preserve a legacy based on what you consider to be lies?"
A lie is an intentionally misleading statement, I think many beliefs in Judaism are based on, not lies, but not truths. At the same time though, Jewish thought is not an empty pit without value. Its history is filled with stories, philosophies, books, achievements and a number of outstanding personalities.
You're telling me I should disassociate from all that just because a few thousand years ago my ancestors wrote some mythology that they believed to be true. I disagree. A heritage is not about truth and fiction. It's about where we came from and how we got to be here and what we received in coming. There is value of a people, a family.
If history means nothing to you, then I'm sure you'd have trouble understanding. Maybe this could help: Is it right to tear down the great pyramids to make way for a strip mall in Gizeh? Is it right to destroy the Sistene Chapel because what it stands for is unfactual? Is it right to raze the Western Wall because you don't agree with the philosophy of the builders?