The First Amendment doesn't grant a right to free speech as such; such a right is assumed to be pre-existing and inalienable (whether one roots such rights in religious belief or secular humanism). Rather: the First Amendment restricts what laws Congress may pass, which might infringe on that right.
I half-agree: many who lean libertarian like to contrast "positive rights" with "negative rights"; and while it's an interesting academic distinction, in my view a purely negative right is indistinguishable from not having a right at all. Perhaps the state cannot proactively ensure my survival with 100% certainty, but a "right to life" is meaningless without some kind of proactive deterrent against violence.
Where I disagree is the "legal" qualifier: while legal protections have an important role to play, so do civil institutions and social norms. Many forms of suppressing free expression are entirely compatible with the First Amendment (economic and social sanctions), and instead have to be defended in civil society, and the court of public opinion.
I see where you're coming from. I just think that if we have to resort to civil institutions beyond courts to enforce something, it's not really a "right". It's some other kind of good or value. So maybe my definition of "right" is too narrow or legalistic--but it is ofc widespread.
I don't disagree, my position here is "yes, and". However one construes "rights" (it's a thorny topic both morally and empirically!), in my view, legal defenses and civil defenses are each necessary, but not sufficient.
The Constitution uses "inalienable rights" for a reason. An individual (and c.f. Citizens United and Hobby Lobby, corporations) is accorded all rights not explicitly circumscribed by a higher form of federal government
That phrase is from the Declaration of Independence, not the Constitution.
The way the Constitution works is that the Federal government only has those powers it is granted, which are limited by items such as the First Amendment, which does not generally restrict individuals (including corporations--there is no "cf" here; corporations are simply people, though they are not 'natural persons", where that distinction matters).