What issues did the Declaration of Independence fail to resolve regarding equality ?

The Declaration of Independence resolved no questions related to equality. Indeed, all it did was declare that "all men are created equal," a fundamental tenet of the thought of John Locke and other seventeenth and eighteenth century intellectuals. It did this by way of providing justification for a political revolution and, as the title implies, declaring independence from England. The Declaration specifically mentions enslaved people and Native Americans, but only as enemies stirred up in violence against "real" Americans. It mentions nothing about class inequality and, despite Abigail Adams's famous request that her husband "remember the Ladies," is silent about gender inequality as well. It is important to remember that the Declaration of Independence is not really a government document, and that it was not intended to establish any framework for government. Over the years, the Declaration has gained acceptance as a founding document of the United States, and therefore its principles have been cited by advocates for equality from Frederick Douglass to Elizabeth Cady Stanton to Martin Luther King, Jr. But the fact that these activists for social justice found it necessary to refer back to the Declaration to support their arguments only demonstrates that it left issues of equality unresolved. In this sense it really was, as Martin Luther King said at the March on Washington in 1963, a "promissory note" that still had to be honored by the society whose birth it heralded in 1776.
https://www.archives.gov/founding-docs/declaration-transcript