Would a coach returning an email invite to the camp be considered a true invite or just an generic email to get you there for money?
You will know which coaches have genuine interest, as they will no longer be emailing your son. Rather, they will text or call. Your son is too young for this to happen, both by age and NCAA rules.
Again, focus on getting better and start formulating the type of school your son may want to go to, i.e. size, location, academics, etc.
You have time, he was 14 less than a month ago! If he's a P5 talent, you will know it and next summer will be busy. If he's a mid-D1, the summer of his rising senior year is when offers will come in.