How did the Declaration of Independence raise questions about slavery?
The declaration of Independence declared that all men have the right to life liberty and the pursuit of happiness. The declaration did not exclude slaves from this right to freedom.
Thomas Jefferson who wrote the declaration was a slave owner up to the day he died. Thomas Jefferson did not believe in slavery but practiced slavery. Thomas Jefferson could not afford to free his slaves. Thomas Jefferson had loans to run his estate, based on his ownership of slaves. If he freed his slaves ( as he did when he died) those loans would have been called and he would have been bankrupt.
Thomas Jefferson was typical of the people in the southern states.
The economy of the south was dependent on slavery. The ideals of the American democracy as expressed demanded that all people be free and have the right to own property not be property.
The declaration of Independence raised questions of how to achieve the ideals of American democracy in light of the economic need of southern states for slavery. These questions resulted in the infamous three fifths compromise in the constitution. Regarding a slave as three fifths of a person is in itself ironic. Was a slave a person who had inalienable rights given by God? If so slavery needed to be outlawed. If the slave was property then they should not be consider even three fifths of a person for representation in Congress.
These questions would ultimately be answer in blood and war in the American Civil War.