Dosung ended his family's trauma after having his own family that he raised filled with love thanks to Lins help.
The concept is lovely, it just wasn't perfect for me. I wish there it was more chronological, jumping from past to present and side characters POV almost made me loose interest, the art wasn't helping too.
Its like im reading a chinese webtoon lol
Have faith my friend, several do play a part later in the story. Not everyone of course, but more than you may think.