The significance of the protagonist's growth in "Solo Leveling" lies in his journey from being the weakest hunter to becoming one of the strongest. This growth not only showcases the protagonist's determination, perseverance, and ambition but also highlights the themes of redemption, power, and transformation in the story. It serves as a driving force for the narrative, as the protagonist overcomes challenges, faces powerful enemies, and evolves both in strength and character throughout the series. Ultimately, his growth symbolizes the potential for change and improvement, inspiring readers to believe in their own ability to overcome obstacles and achieve greatness.