If you're going to raise someone around guns and guns are a big hobby of yours, it's actually pretty helpful to get the kid familiar with them early. There are a set of semi-universal rules around the handling of guns which, if followed, ensure practically no one can be unintentionally harmed by them. If you raise a kid to follow those rules, not only do they see the gun as a mundane object (no curiosity = no reason to play around with it) but even if they did want to handle it, they'd know how to do so safely.

As someone pointed out below, though, at least one of these kids is breaking a big one of those rules. Definitely needs more supervision and education on that.