This is a spine. Look at the size of the vertebrae.
These ones support some weight, they’re big and sturdy.
Now look at these little, delicate ones. They help balance the head over the shoulders, provide protection for the arteries you see running through, and they enclose the spinal canal.
Don’t make them support your whole body’s weight, or you endanger the nerves and blood vessels.
If you think inversions are important, practice handstand and forearm balance, but don’t stand on your head.