Not sure why you're getting downvoted. It is absolutely the case that COVID should make us think very hard about how lucky we got this time. There's no reason to think this couldn't have happened with a virus 10 or 100x as deadly. Given many countries' poor performance containing it, I shudder to think what the next pandemic might look like.
That did happen, SARS in 2003.
It was slightly less infectious, but with a mortality rate of 10%, it was immediately taken seriously in a way that COVID was not.