People wrote songs to capture what was happening around them - what made them laugh, or what made them angry, or sad..... loss, achievement, death, birth...whatever.

This also applies to many, many songwriters regardless of genre or style.

They became folk songs because they were memorable and because they were universal enough to take root wherever they landed

They became folk songs because they happened to be collected in the era of folk song collecting.

Not the introspective, navel gazing, angst-filled singer-songwriter stuff that masquerades as folk-song now."

Plenty of songwriters who are labelled as "folk" songwriters - alongside plenty more who aren't - share your antipathy to navel gazing. You're dealing in lazy stereotypes not reality. Would you like me to post a few randomly selected examples to make my point?