Interesting thoughts. Corn was a basic food for Native Americans long before the whites arrived. It is one of the Three Sisters, three crops (corn, beans, and squash) that formed a basis for their gardening and helped them survive the winters.
The corn you fed them is almost certainly one of the sugar-enhanced hybrids we now eat as corn-on-the-cob. It still has a fair amount of protein and other nutrients so that is good. The extra sugar makes it taste extra good for us. The old field or dent corn is better for cornmeal and that is the kind used in scratch.
Like any other treat it should be fed in moderation. I would not give them a lot on a regular basis. But when I can corn from my garden the chickens get a feast. They get a bunch of corn ear worms as an appetizer and several insect damaged or otherwise damaged corn ears.
You did not hurt your chickens, you just gave them an enjoyable treat. No harm as long as it is an occasional treat.
