Just saw the shot.
Just three remarks for me:
- the jaggies are indeed a problem, minor, but still a problem
- the plane could be bigger on that shot. I understand that you want a contrast between the "small" plane and the "big" cloud, but we're lacking some details here
- the cloud is cool. I don't think it's too low at all, the forest creates a nice effect, kind of jungle-style humidity. The three are cool too, but we can see the ground between them, they are not dense enough. Perhaps a good workaround would be to lower the altitude of the camera, the ground would not be visible anymore and the tree density would look greater.