I skipped the introduction to see if I could understand the legends without first being told what I was reading. I did fairly well. Tolkien describes a world of forests and highlands where kings travel by swift horses. These kings and queens produce offspring who become future kings and queens, if they live. A serpent is slain with a well-forged sword to capture the creature's treasure of gold. A king lusts to possess a powerful ring. Sins of fathers pass on to their sons. Many people die to satisfy the greed of a few. It's just what you expect from mythology.
My favorite line: "Wives oft are wooed by worthless men."
There are lots of names to keep straight: Gudrún, Gunnar, Grimhild, Gjúki, Sigmund, Sigrlinn, Siggeir, Signý, and Sigurd are just a few of the characters. Readers may want to create scorecards to keep the players straight. Names that disappear for dozens of pages appear again when old crimes are remembered. Keeping alliances straight is difficult, partly because of the betrayal of allies. It does not end well for anyone.
Thus glory endeth,
And gold fadeth,
On noise and clamours
The night falleth.
Lift up your hearts,
Lords and maidens
For the song of sorrow
That was sung of old.
Read The Legend of Sigurd and Gudrún if you want to know Tolkien's sources and enjoy ancient mythology.
Tolkien, J.R.R. The Legend of Sigurd and Gudrún. Houghton Mifflin Harcourt, 2009. ISBN 9780547273426