Over many centuries real-life heroes became legends and some of the legends eventually became myths, and sometimes the characters of those myths were seen as gods. The stories become something much bigger than an ancestral retelling because myth fills a need in the human psyche by reflecting it back to itself; by describing it in some way: the symbolic patterns and processes of birth, youth, maturity, old age and death--the endless cycle that all of material life shares--the hero's journey that we all experience in some way in our lives, etc. If you want to know more on this subject, check out any of Joseph Campbell's writings, or Carl Jung.
As someone noted above, this is the mythical lineage of your ancestors so it is yours too. We can only guess at the jumping-off point from the actual to the symbolic and there's sure to be a fuzzy area in between. Take for instance Kari's father Fornjot "the Ancient Giant", King of Kvenland; we can be sure that if he did in fact exist he wasn't a real giant as we think of them but was simply a really big man.
