Speaking from the mum of 2 boys, the whole goodies/baddies and guns phase is simply that- a phase that a lot of little boys seem to have to go through...and with most phases it will pass.
I was always determined that my first born (now 10) would never have a toy gun. But by the age of 3, he was heavily into Spiderman and super heroes, and the toy gun requests followed a short time after.
I assume this all came from pre school as it wasn't something we were really into- toys at home up to that point were all duplo and wooden train tracks!
Anyway, the initial guns were made out of Lego, or sticks or cardboard. So I gave in.
He's since had a succession of various nerf guns and toy rifles.. He's had amazing imaginary games with these, usually accompanied by lots of running about and hiding in the garden. And that's all they were to him. Just games.
They are too little to associate guns with anything other than an exciting, noisy game.
Now at 10, the whole gun phase is behind us. He's still a sensitive and kind young man.
My 2nd son who is 6 has never really been as bothered with them. Different era, different friends and different crazes.
Don't worry about it. You little one is not going to turn into a horrible aggressive adult. He will outgrow them.
(Then he'll be pestering for an iPhone) 😉