There is no "fundamental" version of these myths. In many cases (particularly with Norse mythology) all we know is what was written down by Christian scribes, purposely redacted to fit a Christian worldview. Modern Neopagan ideologies necessarily have to differ because of the dearth of original sources from which to reconstruct the religion, and because neopaganism in modernity would be inextricably linked to modern political, cultural and moral norms (as any religion in any age would be.)
Paganism is well and alive. It is the 5th most popular religious sect in Iceland (and the most popular non-christian sect; excluding atheism). I bet there are even people here on HN that know some people that are pagan.
I’m not exactly sure how they worship their gods, but I’ve heard there are some feasts and artwork dedicated to certain gods. In Iceland most people (even Christians and Atheists) attend a “Þorrablót” which is feasting in honor of Þór.
When I speak of the old gods, I throw Yaweh (God or Allah depending on the sect) in there as well. A 5000 year old run counts as an old god in my book.
[0]https://en.wikipedia.org/wiki/Neopaganism_in_Scandinavia
[1]https://en.wikipedia.org/wiki/%C3%81satr%C3%BA