I’m so glad you enjoyed the cover @coastermaker!
As for the photo being off set, it is because I know many people (including myself) try to follow the rule of thirds. This means that you try to keep the main subject in one third of the photo. If you google “rule of thirds” you’ll see lots of great examples!
Also, for me - I like to put text on top of my photos and so it looks better to have myself offset if possible so the text can fit in there.
I hope that helps!