Do you know what Somerset v. Stewart is?Actually, no.
The Declaration of Independence opened the door for emancipation.;.. read it again and look at the wording.
From the decision:
The state of slavery is of such a nature that it is incapable of being introduced on any reasons, moral or political, but only by positive law, which preserves its force long after the reasons, occasions, and time itself from whence it was created, is erased from memory. It is so odious, that nothing can be suffered to support it, but positive law. Whatever inconveniences, therefore, may follow from the decision, I cannot say this case is allowed or approved by the law of England; and therefore the black must be discharged.
Whatever hypocritical language was in the Declaration of Independence, the effect of it was to remove the American colonies from under the jurisdiction of a court system that had just established the precedent that slaves had human rights.
The British Empire was already on a course to emancipation of slaves. It got there through a series of measures that ended with full emancipation in 1831.
... 34 years before the US finally passed the 13th Amendment in 1865.
We can debate the intent behind the Declaration of Independence - and one school of thought that a major factor behind why independence was declared when it was was the desire of slave states to preserve slavery in light of the Somerset decision - but the effect if the Declaration of Independence was to prolong slavery and delay liberty.