You are right. /s/ Here is a good example: <<Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons>>. If you choose to reply to this post, please carefully consider how Black and Brown Americans would feel knowing this was deeply embedded in this history of their country's founding document. (It is horrible!)
This segment is widely called the "Three-fifths Compromise" in American English. It refers to the fact that enslaved people would be counted as 3/5 of a person for the purpose of determining gov't representation.
From a modern perspective, this section is wholly demented and supports the institution of slavery. This support for the institution of slavery in the founding document of the United States is a terrible stain upon its reputation.
The biggest issue I have with the US Constitution in a modern society: It is too hard to change. (When is the last time the US had a serious effort to pass a new amendment? 1970s / 1980s-ish: Women's equality, but still it failed!) Many successful, younger democracies have found ways to allow non-extremist changes to their constitution, to support "futurism" (my own term) -- the progression of society. Personally, I am a big supporter of regular (frequent), small changes to a country's constitution to support, and facilitate, social change.