PHP image uploader doesn't accept any file-types

I cannot get my PHP image uploader to accept user files and place them into my "user uploads" folder. It always echos the "Cannot upload file-type!" error message, even though every image I have tested the uploader with has been a .jpg/jpeg file. It's very frustrating as I've spend 3 days on this using multiple tutorials and I have also built a successful PHP uploader in the past. I appreciate any help fixing this issue.

PHP: (webpage: server.php)

if(isset($_POST["testUploadBtn"]))   {

$file = $_FILES["myTestPhoto"];

$fileName = $_FILES["myTestPhoto"]["name"];
$fileTmpName = $_FILES["myTestPhoto"]["tmp_name"];
$fileSize = $_FILES["myTestPhoto"]["size"];
$fileError = $_FILES["myTestPhoto"]["error"];
$fileType = $_FILES["myTestPhoto"]["type"];

//explode elements that make up file (file name and extension) 
$fileExt = explode(".", $fileName);
    //convert all file-extensions to lowercase
    $fileActualExt = strtolower(end($fileExt));

    //restrict allowed uploadable file types
    $allowed = array("jpg", "jpeg", "png");

        //Check file-type is allowed
        if (in_array($fileActualExt, $allowed))   {

            //Check for upload error
            if ($fileError ===0)   {

                //Check for valid file-size
                if ($fileSize < 1000000)    {

                    //Create new unique filename using microseconds
                    $fileNameNew = uniqid("", true).'.'.$fileActualExt;

                        //Destination for uploaded file
                        $fileDestination = "useruploads/".$fileNameNew;

                            //Function to uploads file
                            move_uploaded_file($fileTmpName, $fileDestination);

                            header("testlog.php");

                } else {

                    echo "File too big- try again!";

                }

            } else {

                  echo "Error uploading file- try again!";

                }

            } else {

                echo "Cannot upload file-type!";
        }    

}

HTML form: (webpage: testlog.php)

<form id="testForm" method="POST" action="server.php" enctype="multipart/form-data"> <p>

                <h1>Test form</h1>

                <!--If msg variable is not empty- display message -->
                <?php if(!empty($msg)): ?>
                <div class="alert <?php echo $css_class; ?>">
                    <?php echo $msg;?>
                </div>
                <?php endif; ?>

                <hr>
                <b><i class="fas fa-user-alt"></i> Full name:</b>  
                <br>
                <div class='helpBox'></div>
                <br>
                <div class="form-group row">
                <div class="col-xs-4">
                <small><div class='alert alert-info' role='alert'>First and last name minimum</div></small>
                <input class="form-control" type="text" id="testName" name="myTestName" size="40" maxlength="50" placeholder="required*" required/> 
                </div>
                </div>
                <hr>

                <b>Profile photo:</b>
                <br>
                <div class='helpBox'></div>
                <div class="row">
                <small><div class='alert alert-info col-xs-4' role='alert'>jpg/jpeg files only</div></small>
                </div>
                <div class="form-group row">
                <div class="col-xs-3">
                <div class="custom-file">
                <input type="file" class="custom-file-input" name="mytestPhoto"   id="testPhoto">
                <label class="custom-file-label" for="customFile">Choose file</label>
                </div>
                </div>
                </div>
                <hr>

                <br>
                <button name="testUploadBtn" id="testUploadBtn" onclick="return confirm('Create new profile?');" type="submit" class="btn btn-primary">Create Profile &nbsp;<i class='far fa-edit'></i></button>      
                <br>
                <br>

</form>

<script>
    //Display choosen file name in upload form
    $(document).on('change', '.custom-file-input', function (event) {
        $(this).next('.custom-file-label').html(event.target.files[0].name);
    })
    </script>

(Also using Bootstrap v4.4.1 and jQuery v3.4.1)