I should have been killed, or at least hurt

Quite simply, I should have been killed or at least hurt.
That’s the thought that went through my mind as I was getting up, let me paint you a picture, this takes great visualization skills, and I hope enough descriptive skills on my part.
I drive for a living. I drive for a company that I would not like to name, seeing as if they ever found out this happened I would have to fill out reams of paperwork and tell it to 12 people in a room while they make me feel bad about it. This company I work for has what are called pallet trucks. This means that a forklift can remove a section of the bed that is 4 feet by 4 feet and now there is a big hole straight to the ground. I work with compressed gases, and also with liquefied gases. Those are the ones that are really big and silver filled with liquid nitrogen. When I say big I mean 5 feet tall and 750 pounds. So now that you know what I do, this is what I did.
I was finishing up loading my truck for the morning, getting a bit into a rush cause I had a pretty big day. I was trying to maneuver the last of the big liquid containers by pulling backward on it to then slam it up against the side rail by pushing with my right foot to then strap it in. When I pulled toward myself my left foot was in the air to get the most of the pull backwards. When I stepped down with the left foot, I found nothing. No deck plate, just me falling down into the hole while my right foot was still on the deck of the truck. The falling leg won out and I ended up falling toward the ground but also being spun to my belly at the same time. This big liquid container, the one I had just grabbed and pulled backward on, then came down onto my back.
The thoughts that went through my mind were so fast, so insanely quick that all I remember is thinking, “great, dead if not paralyzed.” Now remember this thing weighs 750 pounds, and its five feet tall, so its coming and I cant move, I am stuck halfway to the ground and it hits me BAM.
The container rolled of just as fast as it hit me onto the deck of my truck, I was plugging the whole with my body. Now I have to pick up this thing, not an easy feat after you just got hit by it and you’re shaken up. It was super light to me. My adrenaline was pumping so hard I jumped up out of the hole and picked it upright again then began to do a self check. Nothing sticking out, I can breath fine, I am fine. Wow. I should have been killed or at least hurt, but nothing. Have you ever had anything like this happen before?