Isn't it possible though that things that stand the test of time only do so because they're convenient for living people who use them to advance their own ends?
See The Bible, or frankly any other religious/political text.
P.S Not to take away the fact that those texts are legitimately interesting and valuable in their own rights. But they are by dead people propagated as instruments by the living.
How do you know there is any conflict if they are advancing their own ends within their own group? I'm not religious--I don't believe in general ethical principles either. I'm a particularist. If I were a consistent particularist, I wouldn't advance the general principle not to listen to advice from anyone who has an interest in giving it. I would suggest asking if they were disinterested or not, and to what extent. It's my observation that most of the advice one receives isn't disinterested--but I could be mistaken. For that reason, I have a preference for the advice of the dead, but certainly not all advice they have to give, and mostly for the moral lessons of art and literature--not necessarily explicit guides to conduct.
As a particularist, I would avoid following general principles of conduct in every case, since these do not work in the generality they claim. While I might prefer to use art, literature and religion as a guide to some aspects of conduct in particular cases, I would avoid following to the letter any express or implied general principles of conduct they might contain. With respect to your article, as far as religious texts go, there is Ecclesiastes 9:11.
See The Bible, or frankly any other religious/political text.
P.S Not to take away the fact that those texts are legitimately interesting and valuable in their own rights. But they are by dead people propagated as instruments by the living.