Rights in America are not given by the constitution, they are in-born. The constitution helps enforce your naturally given rights, but it is certainly fallible at this, for example it's initial failing to protect the right to freedom held by slaves.
There are opinions, and there are facts. The right to freedom is a fact. Many of the founders were wrong on one of the foremost issues of their time, slavery, at a time when most of the rest of the world was not wrong about it anymore. As such, we should strongly discount all of their beliefs that are not independently verifiable. For instance, the electoral college. This was created in order to maintain the power of slave owners on government, and should be seen as a tool to oppress the will of the people. The EC is not flawed because it was created by slave owners, but it is suspect due to that, and on further inspection, it turns out to be a tool of oppression.