Several years back I collected a yogurt cup full of corn ear worms when picking some of my corn for canning. I had a group of 10-week-old chicks roaming around so I dumped those corn ear worms on a bare patch of dirt near them. They looked at that worm pile very carefully. Slowly and gradually a couple of the really brave ones started to creep up on that worm pile. A worm wriggled!!! Run away!!! Run away!!!
They didn’t run far and slowly they started to sneak up in those worms again. A worm wriggled!!! Run away!!! Run away!!!
This repeated several times before a young cockerel got close enough to eat a worm. That’s all it took. That entire pile was gone in just a few seconds.
It just takes some time. My pullets now love zucchini. Didn't touch it at first. Then put out yellow squash and they again wouldn't touch it for over a day. Picked at it a bit. This week they demolished a yellow squash. They never eat the skin though. To the OP: don't give up!