Stoner by John Williams (1965)

Arguably the most underrated American novel. Absolute masterpiece that has started picking up steam as a cult favorite over the past 10/15 years.

Heartbreaking stuff, so tenderly executed that one man's objectively depressing reality becomes a series of felt universal truths. It feels particularly strong juxtaposed against modern ideology. Also it's almost definitely shorter than anything else that will be recommended, which is huge for me as someone who typically avoids fiction (and everyone who is struggling with a waning attention span).