They had their own strategies and it would be foolish to think that they didn't have thier own desires and knowledge. They were choosing the European powers which they thought would serve their cause, that is why some supported one European power and the others supported another European power. Their role was great because they knew the ground well.
The idea that people within a state can and should determine the laws within that state is referred to as <span>popular sovereignty. </span>
For one, there wasn't exactly a labor shortage. Because of the economic theory of mercantilism, the colonies were established to produce a surplus of goods. In other words, the only reason there was a labor shortage was because the colonies had been established in the first place for the purpose of creating tons and tons of mostly unnecessary stuff (like tobacco). The best solution would have been simply not to colonize America in the first place, but the colonists could also simply have done the work themselves, or hired labor from other parts of the world rather than capturing and enslaving people.