Your question made me research it a bit for fun. I know I'm a bit late but here:

At first:

Prior to feline domestication, cats hunted small animals like birds and rodents, and before processed kitty food, they were given food scraps and kept humans free of pests. Only when people stopped regularly storing and growing their own food did commercial cat food became available.

Then in 1880s London rotting or diseased food was given out as cat food.

And eventually kibble came about slowly throughout the 1900s. And eventually regulated by the FDA in the US because it could be emergency food in times of need.

Source