Have you carried pails of water? Or Paint? Or garden produce?
Two buckets, even weight, one in each hand work best. And it doesn’t take a very long experiment for the person doing the carrying to figure it out.
Not many generations ago lots of people carried things in buckets every day. It was part of doing chores. Bringing water from well or spring to house and animals. Toting the milk from barn to storage in a cool place for storage or to be processed into butter or cheese. Moving garden crops to storage in the root cellar.
Centuries ago people developed a tool to assist them. It’s mentioned in the Bible. The English word is traced to before the 12th Century.
The example shown below is a reproduction of the tool used by children – this was a family of boys – made my their father so they could carry the water for the family up a steep bluff from the lake.