I will skip most of the introductory comments on the meaning of The United States Constitution, which has already been commented on by both people more educated, more vehement, or both, than myself. However, I will say that while "The Constitution" is thrown around as a great hallmark in human liberty, it is more a structural document relating how the government works than an ode to humanity's highest ideals, etcetera. In fact, there are only a few guarantees of civil rights granted in the Constitution. I will enumerate these below, in order of appearance:
- Habeas Corpus: One of the most basic civil liberties, and recently one of the most contested, is also the first mentioned. This is the basic civil right that says the government can not kidnap a person, that the government must always declare why and where someone is in custody. Strangely enough, and something that a very strict constitutional constructionist might have fun with, this is listed under "Limits on Congress", so perhaps it is just Congress that can not suspend Habeas Corpus, while the Executive can. Although it is clear that the founders found the concept of Habeas Corpus important, which makes sense given their circumstances.
- Bill of Attainder and Ex Post Facto Laws: Immediately below Habeas Corpus, this provision states that Congress can not pass laws that single out a certain person, or pass laws that retroactively make people's actions illegal. The importance of these for civil liberties is obvious.
- Prohibition of the above two from state governments: Before the 14th Amendment, and (for some), even after, most of the civil rights granted by the United States Constitution were taken to only refer to the federal government. In other words, because the United States Congress can not prohibit free speech, does not mean that the states could not do so. However, here, we have the states explicitly banned from undermining civil rights. This is the only such prohibition in the original constitution.
- Trial by jury: All criminal cases shall be tried by jury. This is an important civil right, and again would be seen by the founders as a protection against imperial and arbitrary punishment of crimes.
- Limitations on the definition, trial and punishment of treason. Article III, Section 3, defines treason as only engaging in war against the United States, or aiding an enemy. In other words, disagreeing with the government is not treason. In addition, two witnesses or a public confession are needed (at least) to obtain a conviction. And, after conviction, there is a limit on the punishment for treason: "corruption of blood", meaning punishment or disenfranchisement of the traitor's family, is prohibited.
Given the climate that the Founding Fathers were working in, one of the reasons for this is obvious. I also believe that it may be a structural move, as a way to preserve a federal system of government. Given that the United States was going to be a collection of states with a variety of political interests, this may have been included to guarantee that regional interests that were opposed to the federal government were not viewed as "treason".
- No religious tests: Before the First Amendment in the Bill of Rights, this is the only mention of religious freedom in the Constitution. No religious background is required to hold office in the United States. Along with being a civil liberty, this was also probably included to ease the fears of the different states. Since many of the states had different dominant religious groups, some hostile to each other, this may have been included so that, for example, Roman Catholic Maryland would not have to worry about being able to elect congresspeople.
Along with these, there is also a section guaranteeing "Republican government". In a constitution full of vague phrases, this is one of the most vague. Each state is guaranteed a Republican government, which could be taken to mean that at the very least, they must treat their citizens as citizens. However, in practical terms, "Republican government" offers no specific protections of civil liberties.
So then, the civil liberties granted by the original constitution are fairly narrow, and mostly refer to either narrow concerns that were important to the generation that wrote the constitution, but are less important today. Or, they were probably included less out of a belief in individual liberties as a way to assure the various states that they would have their interests protected in the new government. In any case, while the constitution is a very ornate structural document, before the Bill of Rights was introduced, it seemed to have very little in it to protect civil rights as we now understand them.