Yes a human can hang from a power line with their feet and legs in the air and wouldn't get shocked because they are not creating a path to the neutral wire or ground which is what causes a shock.
This is why you see birds and squirrels on power lines without getting shocked from the live power line since they are not touching the neutral wire or ground so they do not get shocked.
Now if you touched the ground wire while on a live power line then you would get shocked and likely killed as a result.
Still you should never try to sit on or touch power lines at all because you could get killed.
When power line workers are crawling on live high voltage power lines they first go through process which charges them with electricity and bonds them onto the power line which prevents the person from getting shocked when crawling across the power line.