DH's mate said when DS was 6 months old that a great first food for babies is hot chips. And tiny teddy biscuits are also good to start babies on
DS eats healthy most of the time but he will have tastes of a variety of foods. He has sipped on milkshakes and tried ice-cream and biscuits and all sorts of things. I grew up with no junk food and then became a junk food junkie when I moved out of home and didn't eat vegies for like a year.
I don't believe in "treat" foods - that's implying food is a reward - that in itself is an unhealthy attitude. There are not good foods and bad foods, there are just foods you should eat a lot of and foods you should eat a little of. I want DS to understand that from a very young age.