Although you did not present it, the lines to which the question refers present slavery as something that was maintained in the country, even after the whole concept of freedom for all.
Answer:
because slavery remained a contentious topic in the rebelling colonies
Explanation:
The declaration of independence reinforced the need for freedom in America and established that this would be a factor that America would fight for. However, due to economic interests and ideological polarization between states, slavery became a controversial topic and was not included in the declaration of independence to avoid internal conflicts.