<Try thinking if you were another form of intelligence, and you wanted to contact us humans. How would you do it?

With a lot more intelligence.

One would like to think that if I could travel across time and space, I might figure out how to operate a stupid cell phone. The whole idea behind "communication" is trying to put your information into a form the other person can easily understand.

If making pretty pictures in corn is the best they can manage given the thousands of forms of human communication available to them, we probably wouldn't learn much from them anyway.

Now, if the aliens are just talking to each other instead of us....Maybe the entire thing is just different gangs of "teasers*" tagging our planet. Or maybe real estate agents marking places for six thousand story condos when they take over the Earth.

*See "Hitchhiker's Guide to the Galaxy"