The distinction is also not that important. The line between indentured servitude and slavery is pretty thin.
Although to be fair a lot of the first Europeans that came to the Thirteen Colonies were also indentured servants. The trip was long, dangerous and expensive, so it's very understandable that the people paying for the workforce to move, which is usually rich colonists, would demand a long term commitment from the labourers instead of the risk of them running off into the depths of the continent to settle there.
Although to be fair a lot of the first Europeans that came to the Thirteen Colonies were also indentured servants. The trip was long, dangerous and expensive, so it's very understandable that the people paying for the workforce to move, which is usually rich colonists, would demand a long term commitment from the labourers instead of the risk of them running off into the depths of the continent to settle there.