I didn’t read the whole thread, but here’s an old one that doesn’t get into Gift giving economies directly, but has a lot of discussion on the “barter didn’t precede money”-idea:
Basically the development is likely to have been more one of informal “share your surplus”, expect others to share later local economies, that developed into more formal “I gave you this, you owe me the equivalent in the future” economies as societies became larger and more interdependent.
And this sharing is likely to have involved “giving” things away, expecting something in return, whether it be other gifts, or power.
Ref for instance Potlatch - Wikipedia
ETA: Or just read the article Babale links to …