Only protecting the rights of living human beings sounds like a terrible idea. It sounds weird to say it, but dead people have rights too - and so do some things which aren't human at all. Kittens, for example. A sufficiently narrow reading of "only" protecting the rights of "living human beings" could effectively put a stop to, among other things, great huge chunks of wildlife conservation efforts at a government level.
Section 2 sounds really, really odd to me. It sounds wrong on multiple levels. For example: what constitutes an institution? Who has the authority to grant an institution the privilege of existence? Since when is existing ever a privilege? And what is the purpose of this whole line?
Honestly, the more I read this thing, the more it sounds like a terrible phrasing of a suspiciously radical concept to begin with. I would imagine that 'A corporation is not a person and does not possess any of the rights which are otherwise exclusive to people" would rock the boat enough.
And even then I'm not sure if that's sufficiently specific. When you really think about it, a constitutional amendment of "corporations are not people" wouldn't be terribly helpful; nobody's ever actually seriously claimed that they literally are, or should be. (I've never heard anybody claim that corporations should have a right to vote in elections, for example.) What we actually want is for corporations to not have certain rights and abilities that would otherwise be the sole domain of individual people and governments - but (I assume) we want some of those things to remain. The ability to sue and be sued, for example. Or the ability to have money and property. (Physical, not intellectual.)