I see nothing to indicate this was made by man.
The markings are not even remotely like any petroglyphs I have ever seen out west. The natives did not carve their symbols into the stone. They pecked into the desert varnish that occurs on rocks to make them (symbols) permanent, not any kind of deep incisions like on your rock. I realize that you are back east and I am talking about the desert southwest. Maybe they did this back east but I doubt it. If they were going to chisel a message into a rock they would have used a softer rock to work with.
Send a picture to someone at your State university Anthropology dept, ask if they have ever seen "carving" like this on any other native artifacts. If they can show you other examples of marks like this then maybe you are correct. My guess is they will send it on the the Geology dept.
Mother nature is wondrous in her diversity. It is natural.