Ah, hmmm, let's see. I think my suggestion would be to set your main page to show your latest posts. Then create a sticky post with your picture in it. As a sticky post, that post will always show at the top of the listing of posts. We can hide the post meta data and title and such from that sticky post so that only your image appears.
If you would like to do that, go to Settings > Reading and set your front page to show your posts. Next create the post for your image and insert your image, set it as a Sticky Post and then publish it.
After you do that, let us know and we can help hide all the meta data and stuff from that sticky post.