When the Bible says it's appointed unto man to die once, do you think we misunderstand it?

Jesus raised Lazarus from the dead and he died again.
We could say it was a show of HIS power to prove He is the son of God.

So are we all really meant to die just once and after that be judged?

That verse states one of the ordinances on which the world was created (Ecclesiastes 3:1- and though for all men it is unavoidable, yet God Who set the ordinance interrupts them at His pleasure. Same for Enoch, Elijah and saints alive at rapture. Another such interference is the standing still of the sun and moon, dividing of the red sea, opening of the mouth of the donkey, bringing water out of the rock in a dry desert, etc