Looking for knowledge on antique chair

I bought this from a woman who described it as sitting in the corner of a room for 15-20 years and it was probably passed down from her family. It's made of oak but has been painted. The only piece that isn't oak is the center where you would sit and it looks to have been replaced (pictured). It looks to have been cut with a circular saw (pictured) and then jointed by mortise and tenon (pictured) and there are some (what looks like dowels) on just one side of the seat (pictured). It has screws (pictured) and doesn't appear to be glued anywhere. One of the leg braces is missing on the bottom (pictured) and it gives a look as to how the other leg braces are attached. Two of the screws on the top have been ripped from the wood also (pictured). I would like to know if anyone knows anything about this chair. About how old is it? What might it be work? Anything at all. I like this chair and will probably remove the paint and restore it when I learn how to properly do it to an antique.