I also checked out your novel. I think you shouldn't limit your novel to 300 chapters. You made a rough draft for a novel that was good, but you didn't consider development for an idea and your writing skills. It will get better with the more you write.
Novels and Web novels are essentially different. You should aim for at least one million words. It would be better if you could drag one situation into a few chapters.
You mixed everything in the first three chapters because of the competition. But you can split them into different parts. Like 1.Village (you can describe MC' situation) 2. Past (Maybe one of his aunts will tell them bedtime stories and describe the past. This is required because you mentioned deleting previous chapters.) 3. Attack(from giants) 4. Journey(they will leave for a safe place.) 5.Danger, preparation or bravery(MC will send others and prepare to fight with the giant.) 6. Fight.
Ignore the last paragraph if you are not comfortable writing like that, but my advice is you should consider it because most web novels are written like this.
Also, check out 'Book of authors'. That might give you a new perspective on web novels.
P.S. i can't wait for your next chapters.
I will write reviews for others as soon as I can.