Here's why:
* Themes: His poetry often explores themes of idealism, imagination, individualism, rebellion against societal norms, and the power of nature. These are all hallmarks of Romanticism.
* Style: Shelley's poetry is known for its lyrical beauty, vivid imagery, and emotional intensity, all key elements of Romantic style.
* Influence: He was deeply influenced by earlier Romantic writers like William Wordsworth and Samuel Taylor Coleridge and in turn, influenced later poets like Lord Byron and John Keats.
While there are aspects of his work that may not strictly align with all Romantic ideals, his overall themes, style, and impact on the movement solidify his place as a prominent Romantic writer.