Django viewset error: 'QuerySet' object has no attribute 'title'

I'm trying to create a ViewSet for the Course model (to simply display all courses), but I'm getting the following error when trying to access it. I'm new to creating ViewSets and Django in general, what am I doing wrong?

Django 2.2

Error

AttributeError: Got AttributeError when attempting to get a value for field `title` on serializer `CourseSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `QuerySet` instance.
Original exception text was: 'QuerySet' object has no attribute 'title'.

CourseViewSet

class CourseViewSet(viewsets.ModelViewSet):
    def list(self, request):
        queryset = Course.objects.all()
        serializer = CourseSerializer(queryset)
        return Response(serializer.data)

CourseSerializer

class CourseSerializer(serializers.ModelSerializer):
    class Meta:
        model = Course
        fields = (
            'id',
            'title',
            'description',
            'active',
            'individual_result',
            'course_duration',
            'video',
            'manager_id'
        )

models/Course

class Course(models.Model):
    title = models.CharField(max_length=255, blank=False, null=False)
    description = models.CharField(max_length=255, blank=True, null=True)
    active = models.BooleanField(default=True)
    individual_result = models.BooleanField(default=False) 
    course_duration = models.CharField(max_length=255, blank=True, null=True)  
    video = models.CharField(max_length=255, blank=True, null=True)  
    manager_id = models.ForeignKey(User, on_delete=models.CASCADE, null=True)

    def __str__(self):
        return self.title