I'm not contradicting myself at all. I said that what constitutes universality is subjective, thus universality is an unreliable metric for measuring the value of literature. This is entirely different from asserting that the value of all literature is relative. I don't disagree that some literature is bad and some literature is good, however I don't think universality is a very meaningful concept to reach those judgements.
Your argument is amounting to a "No True Scotsman" one. Any book that's brought up to challenge your ideas is immediately dismissed as "not literature" without any clear definition of what actually constitutes literature.
Those so called universal experiences exist in pretty much any work of art. Upton Sinclair's Jungle you dismiss as socialist propaganda. However, isn't the struggle of a working man to support his family arguably universal, it's all about life, liberty and the pursuit of happiness after all. Sinclair was a socialist, but he was a distinctly American one. The Jungle is hardly a spectacular book, but it has continued to have resonance enough that it remains in print 100 years after it's publication.