This statement is not to be believed nor is it backed up with any hard data.
Sometimes something that is presented as fact is done so for sinister reasons or to propel a particular ideal. It's pretty common when nations have wanted to go to war to spin certain events so that the truth can look more favourable to their cause.
Other times, humans have just been known to get something wrong. There's nothing inherently bad about this, so long as you are willing to accept your theory or understanding may one day prove to be incorrect.
We shouldn't hide from our mistakes. We should embrace them, especially when they were not perpetrated through evil, but through ignorance.
With all that understanding it's still pretty hilarious to go back in history and gaze at our idiocy. It's like looking at humanity's own fail compilation.
Many of the following have at least a smidgen of truth in their origins. Nothing presented is a flat-out lie; more an exaggeration or misinterpretation. But looking back we can really see, much like reading our schoolworks from years gone by, that we used to be kind of stupid.