animal crackers in my soup...

Native Americans represented various animals (deer, elk, alligators, birds, otters, snakes and even gigantic men) in effigy mounds. They often used these mounds for burying their departed. This form of representing animals makes them sacred, in a way, by associating the shapes of the mounds with the dead. A sensitive subject, if you will.

While in the Lascaux cave, these animal representations could be of religious significance, but not necessarily. These could be drawings/paintings of an example like Mickey Mouse: they could be just pictures, no real significance. Maybe a decoration of living space. (Christopher Lowell should check this out).

Although today, animals are still represented in a variety of ways, in sports teams, business mascots/logos or even maybe animal crackers. Still being represented, they should not be held "sacred" because they represent other things (sports teams/business). Not so much a sensitive subject as loved ones passing away. 

These representation of animals (in regards to the mounds), has religious significance because it involves the burial of sacred relics and lost-loved ones passing to an "afterlife". These animals are important religious symbols because with an association with burial, they become sacred symbols. Opposite, Mickey Mouse or animal crackers couldn't be (or at least shouldn't be) considered as sacred because these examples aren't associated with sacred relics, passed loved ones or an afterlife. 

Although animal crackers would be sacred in my view of an afterlife...

kidding.