The consenting age is as low as it is because men are in power and they want to leverage girls lack of knowledge and worldliness. They're not ready to be wives or parents, or catch a lasting disease or recover from a date where someone can overpower them more easily because they're not physically grown up at that age, that's the truth.

No, they're not adults, they just have the right to consent. That doesn't create morality. And it doesn't make up for the power differential once the man is older than 30. 25 is the actual age the brain stops developing so 21 would be wiser. In general, teens are just trying on pieces of adulthood and failing a lot.

If men had a more robust culture of honor, kindness and truthful discourse towards women rather than deception and "use" of them then we wouldn't have this problem, most likely.