Your entire generation definitely didn’t make it just fine, lots of kids were killed, abducted, assaulted, raped, traumatized, or just disappeared. That doesn’t mean anything on its own about how we should live today, but they didn’t make it just fine.
And yes, traffic fatalities were much higher before seatbelts, but they still only affected a tiny fraction of kids. The vast majority were just fine.
One thing I always think about when reading these posts: the complaints about how kids never roam free anymore are also accompanied by claims that abductions are incredibly rare now. But how do we know they’re not incredibly rare because kids don’t roam free? It feels like claiming that you shouldn’t have to wear your seatbelt because traffic fatalities are much lower than they were when seatbelts were introduced!