These two rocks are in an area in Arkansas that had a lot of bushwhacker activity during the Civil War and directly after. I think the stones were nothing more than trail markers giving directions to different places but could be wrong. There are a couple known hideouts in the area.
In order to really see what all is on the rock; you could use mix up some talcum powder and water and use an artist brush to "paint" the marks you see. This work best in the dark with a dim flashlight or lantern shining low across the surface. These modern lights just wash out the surface and you can't see the grooves very well. I would bet that are features you are missing. Sometimes just dry talc and a big paint brush swept across the surface works good too.
The design elements on there, a bow and arrow, turtles, make it a good chance it is Native American in origin. Native American rock art is found in every state. Those are common designs seen in petroglyphs.