I keep fruits and vegetables cut up and ready to eat in the fridge.
Sliced cheese and crackers.
I mix up cream cheese, roasted red peppers, sharp cheddar, Worcestershire sauce, salt, pepper, a bit of paprika or cayenne pepper and fresh herbs that I happen to have (basil or parsley, thyme, maybe). Dd loves to dip pretzels in this or spread it on crackers.
We often have overripe bananas, so I make banana bread regularly. I also keep canned pumpkin on-hand for pumpkin bread. Carrot cake is good, as is zucchini bread in the summertime. Sometimes dd likes to have a shmear of butter and honey on my homemade regular bread fresh out of the oven.
Also, for fruit that is getting ripe, I whiz it up in the blender with some milk or yogurt and make homemade popsicles. We keep frozen strawberries on hand, so a ripe banana, some strawberries and plain yogurt make a really delicious smoothie or popsicle.
Dd loves little tea sandwiches. I don't bother to cut of the crusts and slice the bread thin. Or I buy these mini pita pockets and let her stuff them.
The hummus we make doesn't have tahini in it. It's just chickpeas, garlic, olive oil, lemon juice, parsley, salt and pepper.
Mini bagel and cream cream or peanut butter.
I make ww waffles and freeze them. Dd likes to toast them and eat with Nutella. I realize in the US Nutella doesn't seem healthy, but it's all natural (and dd cannot have anything that has preservatives or additives in it) and is really the peanut butter of Europe. She discovered it when we lived there and still enjoys it.
A favorite after-school snack is popcorn.
Wraps that are cut in to bit-sized pieces. Some cheese spread, lettuce, shredded chicken in a whole grain or flaxseed wrap would be a really simple idea.
Guacamole and chips... pita or tortilla.
Hope one or more of these ideas help. Dd isn't picky, so I'm not sure what picky eaters eat. Good luck!