Poul Anderson's "Sargasso of Lost Starships" (novella, space opera, free): Humans humble god-like aliens
This is one of the impossible adventures in the style of early sf: humans travels hundreds of light-years, only to fight with swords & spears, against aliens so powerful the humans ought not to have any chance! About half way through, I'd to shut off the mind & just kept reading without being critical.
"Sargasso" of the title apparently comes from Sargasso Sea, a region of Atlantic Ocean bounded by sea streams. In the story, there is the Black Nebula - a huge cloud in the skies - that acts a kind of Bermuda Triangle: ships entering it simply vanish, & are never heard of again. I don't know if the real Sargasso Sea is part of Bermuda Triangle.
This is the story of human adventurers entering this forbidden region of galaxy, & surviving - with heavy losses. There they will meet & overcome psychopathic ancients of enormous magical powers.
Fact sheet.First published: Planet Stories, January 1952.
Download full text in multiple formats from Internet Archive.
Related: Stories of Poul Anderson.