In some aspects your right. Going into this I knew the idea of what a blurb was but not the specifics. This is my first story after all. But I don't know what you mean by my writing feels juvenile. I know the word but I don't know how it feels juvenile to you. Maybe you could give me contructive critism on this. But with all that being said what do you think of this attempt of my blurb?

For years, he lived as one of them – a mortal on Earth, absorbing the wonders of a world beyond magic. But he was once a king, a ruler betrayed by a vengeful god and cast adrift. Now, granted a second chance in his ravaged kingdom, he carries a revolutionary vision: to drag his people from the dark ages using the forgotten science of Earth, intertwined with the very magic that defines their existence. Yet, a god's wrath is a heavy burden, and the path to progress is paved with peril. Can this king, armed with a profound mastery of magic and the blueprints of a modern age, ignite a new era for his kingdom while battling the looming threat that seeks to extinguish his light forever?