While I agree with you that it probably isn't a ghost I don't think this pixelation example proves that. This pixelation is happening because the image is brightened (it probably wasn't of great quality to begin with).
I mean, look at the boat. It has some of the same pixelation around it and we don't doubt it's veractity! So this alone doesn't prove/disprove anything.
If I had to guess, I would say the "eyes" are far off lights and the "body" is maybe some faint reflection on the water. It just happens to look humanoid when lightened. All taken together it looks like a ghosty thingy.
I reserve the right to be wrong though!