No..they felt they knew...because that is a human trait. People think they know stuff.
You are grave robbing right now and revising history. They felt they knew because they had data and evidence. There methodology however was just to archive the results rather than the method. It was the same process as science textbooks today, except they just had less raw data to go off of because their archival methods were limited to their technologies. They had to lean on there spiritual and philsophical methods. You sit on a high horse in the future with the ability to document your own individual life visually for everybody to see. A person from the past would love to have that because it would make their archival processes easier to produce. Education of future generations was very important to them so getting the history right would also be. They didn't just "feel" they knew, they knew because they trusted the methodology there were using. That methodology had flaws, but they didn't get everything wrong. In fact they got things right that should make the scientists of today try to ascertain their true methods. However they get stuck in the vortex of Genesis 1:1, just as you are.