Hoo Boy!
That's some dangerous ground, right there.
Ever tell a kid to leave something alone? Some will, some are going to take a little 'educating'.
If a child wants to locate something, they will, sooner or later.
Can a determined child find my guns (well some of them)? Sure. A determined child can find a penny in a grain bin. The trick is to dampen that determination by teaching kids what not to do.
My father had a closet in which resided all long guns. It was open, the ammo was on the shelf. We had been told that if we wanted to go shooting, we were to ask. (rural setting). If, however, we ever took a firearm without his express authorization and approval (and supervision), we not only would not be allowed to shoot for a year, but we wouldn't (when we were older) get to go hunting that year, either.
We didn't mess with the guns, we didn't let our friends mess with the guns. Period.
We knew where the handguns were, too, and that they were loaded, but we did not mess with them at all.
Now, there are those who might debate this, but I don't see my father as irresponsible. He just raised responsible kids.
YMMV, one size does not fit all.
I am sure you have seen news reports or read about them, where toddlers or young children find loaded guns and then accidentally shoot their little friend, brother, or sister and even their parent. It has happened many times.