I hold that objects that are very fit for purpose are designed by 1. humans e.g. good knives 2. natural selection and natural physical processes: for design to be the case there is no need to posit a Designer except for human artefacts which are designed by human designers. I suppose that most people think of God in the story of The Garden and the Fall as the big final cause. I prefer to think of God in the story not as final cause but as necessity or determinism. And the latter interpretation is why I can think of Adam and Eve as fallen into freedom and Angst.Though I don't think the comparison between Sartrean conceptions of freedom and the fall necessarily fit. In fact, I'd say minimally so because Sartrean conceptions of freedom begin from an atheistic premise: that objects, which have a predetermined functionality - i.e. a knife has a predetermined essence, there is essential properties about it, as it has been designed. Meanwhile, humans lack this: "existence precedes essence" for persons, as there is no designer who created us.
I like your comment that Krishna was trying to tempt Arjuna to be inauthentic. I suppose that Sartrean authenticity is very Western. I bet Sartrean authenticity was first invented by Martin Luther