"I am a genji in training" was originally a post made by EnderSam 2oo7 on the site known as Google+ in the "Overwatch" community. Sam had written the line with the caption of his own face, which eventually blew up to be a meme spreading across some of Google+, and as of October 30, 2016, 4chan.

Some other users have also made their own "I am a (Overwatch character) in training" by posting their own faces with actions, looks, and/or weapons relating to a specific Overwatch character.

The original post can be found here: https://plus.google.com/102819148891109033007/posts/Gqt6cmoYKEt