Children like to "dip", so giving them things to dip and eat is fun for them.
Cucumber, celery, carrots and other finger veggies like jicama go over well, as they aren't too strong tasting. Fruits of all sorts can be fun.
Banana "pudding" (nuts or seeds and their butters with dates or other dried fruit smashed or pureed with a bit of lemon to prevent browning) and smoothies go over well.
I like to make a low fat "Ranch" dip with silken tofu (they can't tell it's tofu if you don't tell them!). Hummus was a favorite with my little one and my charges when I was a nanny and preschool teacher.
I also made "hummus" with other beans and seeds too.
You can make sweet spreads too using dates or other dried fruit and nut or seed butters (check for allergies).
Beast of luck!