Existentialism says that because the universe is meaningless you need to create your own meaning. That applies to humanity as well as it does an individual.

Right now, Humanity has no "goal" as it is currently with AGI - we haven't figured out a seed goal for AGI yet. In my view we should agree that the meaning for humanity is to create our successor: AGI. This fits into the evolution progression, only it becomes self directed.

But by your own argument, that's just a meaning that you made up. Why should the rest of us view it as having any validity whatsoever? Why should the human race decide that that goal is the one they should have, as opposed to, for example, destroying all life on earth? (That's the problem with existentialism - you can pick anything as your meaning.)

Well that's my task...to sell it so that people will buy it.

Things can have a purpose without a god being there to give it.

They can? The way "purpose" was used in the original post, there just about has to be someone there to intend.