I used to admire the US constitution. I've grown up now.
Who could possibly be opposed to human rights - i.e. human beings having rights? And indeed, the US constitution does appear to be largely about rights.
Over the years I've increasingly leaned to the view that these rights are mostly a legal fiction, and that the things that are supposedly rights are highly subjective political footballs. Nowadays I think of a constitution as a largely non-political set of rules for how government works; i.e. it's a description of a mechanism, not a description of an outcome.
From that point of view, the US Constitution is an awful constitution.