Yep. It was a long time ago, and the galaxy has since gone through thousands of years of oppression at the hands of the Corpus and the Grineer, both of whom are not interested in preserving history that contradicts their propaganda.
The void is a place. And it's a place that does not conform to the laws of consensus reality. That's destructive, yes, but it's more complex than that. The most obvious effect of void contamination is it causes madness. That's why you face a bunch of "corrupted" corpus and grineer in void fissure missions. They've been driven mad by the void and are operating according to goals and motivations unknown to any sane person. It's actually super weird that the Tenno aren't corrupted by void fissures and by travelling to the void. You can be exposed to void energy no problem and you're basically fine. Maybe you'll learn why that is in a future quest.
Shoot me any more questions you have, I like explaining stuff without spoiling the plot