Lot's of people say "God given"... tho indeed I was being provocative when I wrote that. Reality is... I really don't care whether people say natural rights (which also has a problematic history) or God given.
But the guys that wrote the constitution did not consider that they were "giving" us rights... surely you mean that in a different way... I prefer to understand it as they affirmed or verified those rights that are implicit to being a free human being. If you read the Federalist Papers, you can learn all about what those smart dudes thought, researched, understood, believed, and enshrined in a blueprint for a new Republic. It's worthwhile reading.
Yes, I didn't exactly mean "given". More like "protected in writing".