Photos that spark conversation or pique curiosity are also good choices. Either he has low self-esteem, doesn't care about pictures, or that picture is not at all indicative of him. He tries to impress you with humblebrags.
It may surprise you to know that a lot of our members are single parents looking for a relationship. Once you register on the site, you can start sending messages. At least, that's what he wants you to do. Ask her questions about herself as well.