MVC 5 AJAX Post DIV Form Seriaiaze to Action Model Always Null?

I cannot post Div values to an MVC Action model, always null. I've tried many article examples and still get nulls. Capturing the .serialize in an alert looks like the pic below. I'm not understanding how an MVC Model can accept a serialize object. It looks like a simple querystring...


Here's my code so far:

$.ajax({
        url: 'Posts/Save',
        data: $("#form1 :input,text,textarea,select,hidden").serialize(),
        type: 'POST',
        contentType: "application/json; charset=utf-8",
        cache: false,
        success: function (result) {
            alert(result);
        },
        error: function (error) {
            alert("ERROR: " + JSON.stringify(error));
        }

    });

[Action]
 public JsonResult Save(PostUpdateViewModel model)
 {
 }