Early human minors (until a century or two ago) used to have sex, engage in hebephilia and pedophilia, and underage teenage girls used to be mothers. This is how we still have grandmothers today who married and had kids before the age of 18. So yes, your question is wild and scientifically ignorant. Porn has always been harmful to minors, and in fact, specifically more to minors or anyone under the age of ~25, because that is when neural connections stop forming and adjusting. The neural linking and development starts to slow down by the age of 15. That makes underage minors even more vulnerable, as they hit puberty, have raging hormones and are also at risk of sexual abuse.