Why do you think that J stand for glasses ?
The dates are the more important clue there. It's Steve
Jobs.
So why not 5S instead of 5J? Seems more logical to me
.
yeah, it is really hard to work it out, even though it is interesting it would be better if each picture would stand for only one character
edit: how to know whether it is upper case or lower case letter?
Actually, if you count them, you will see that there are
exactly 51 puzzles that needs to be solved. There are also 51 characters in a private key, so it's safe to assume that each image stands for 1 character.
I haven't figured out the upper/lowercase problem yet.