While I appreciate your reverence to the beginnings of our country, there are flaws in the foundation of our system of governance. I think those flaws were initiated by those founding fathers that were banker shills (Hamilton et al), but it may have gone even deeper than that. They were after all almost all Masons.

With respect to the specifics of this cartoon, they are using a false equivalence as the argument. They are suggesting because the document didn't explicitly solve all moral dilemmas of the day, that it had no merits. Turning that back around is the rebuttal. The DoI states explicitly that "all men are created equal" where by men it can be inferred all humans, since men = humans in the vernacular. This by itself negates much of the argument they are presenting, even if the details of that declaration still needed some ironing out.

The constitution got a lot of things right. It was based on the writings of John Locke which got even more things right. It certainly does a whole lot more for the individual (which is real) than Marx's social construction which focuses on "the greater good" which is not real, but rather a contrived idea.

The greater good is an ephemeral idea, presented as the inevitable and only moral goal. It is perversion of a group of individuals who are born sovereign into an imagined group of individuals who require a sovereign to rule them by construction of the system it proposes, even though it promises the exact opposite.

We do need to make some changes to the original founding documents. They had inherent flaws that were inevitably exploited. But to throw the baby out with the bathwater, as this cartoon suggests dismisses all the good that came with the minor bad, which were in this case merely deeper issues that were allowed by the constitution to be solved at a later date, when the populace was ready to face it.