When i click submit button it first inserts a default null values on first row then the next row would be the values that i inserted – Jquery ajax

I’m new to MVC asp.net jquery ajax and hoping you guys can help me give insight on my problem.
Thank you so much any answer would be helpful.

I’m just having a self exercise that i saw on some online group to help me gain more knowledge on how to implement jquery on asp.net mvc any advice would help.

Controller
public JsonResult AddJob(jobdetail job)
        {
            using(jQueryAjaxEntities db = new jQueryAjaxEntities())
            {
                db.jobdetails.Add(job);
                db.SaveChanges();
                return Json("Success");
            }

        }

Heres my AddJob view
Whenever I remove the script src it’s saving normally, can anyone explain me why is it like that?

  <script src="~/Scripts/jquery-3.4.1.min.js"></script>
<script>
    $(document).ready(function () {
        $("#btnSave").click(function () {
            var JobModel = {
                TaskName: $("Task_Name").val(),
                Description: $("Description").val(),
                DateStarted: $("Date_Started").val(),
                DateFinished: $("Date_Finished").val(),
                Status: $("Status").val()
            };
            $.ajax({
                type: "POST",
                url: "/Home/AddJob",
                dataType: "json",
                contentType: "application/json",
                data: JSON.stringify({ job: JobModel }),
                success: function (response) {
                    window.location.href = "/Home/Index"
                }
            });
        });
    });
</script>

@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        @Html.HiddenFor(model => model.JobID)

        <div class="form-group">
            @Html.LabelFor(model => model.Task_Name, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Task_Name, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Task_Name, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Description, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Description, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Description, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Date_Started, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Date_Started, new { htmlAttributes = new { @class = "form-control", @type = "date" } })
                @Html.ValidationMessageFor(model => model.Date_Started, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Date_Finished, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Date_Finished, new { htmlAttributes = new { @class = "form-control", @type = "date" } })
                @Html.ValidationMessageFor(model => model.Date_Finished, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Status, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Status, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Status, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group" id="DivSave">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Submit" id="btnSave" class="btn btn-default" />
            </div>
        </div>
    </div>
}