There is an enormous difference between a lure, and an artificial that imitates or suggests what a predatory fish eats.
Both plugs, crankbaits and certain "flies" can be made to work like, and look like small fish for instance. There are some plugs that look like mice for example, and predators such as pike, I am sure, take these artificial baits for mice, just as they take many of the plastic baits which look and work like fish. They even feel like fish.
There are also some flies, Lefty's Deceiver for example, that look just like a small fish.
But some flies and some lures look like nothing on this earth. Yet fish take them; what they take them for I do not know, they are among the true lures. Flies such as blobs and Vivas are lures. Flies such as buzzers and daddy long legs are imitations of what a predatory fish eats in nature.