The U.S. Constitution was the result of compromise, a major one being no statement against slavery. The alternative would have disunion. The Constitution is not a static document; it can be amended.
Speech of Benjamin Franklin:
https://usconstitution.net/franklin.html
Excerpt from the speech:
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Jefferson --
"I am not an advocate for frequent changes in laws and constitutions, but laws and institutions must go hand in hand with the progress of the human mind...institutions must advance also to keep pace with the times. We might as well require a man to wear still the coat which fitted him when a boy as civilized society to remain ever under the regimen of their barbarous ancestors."