You might think that everything that can be invented is invented. The limitation is not in what there is, but in what you can see. We like to view ourselves as somewhat exceptional, but many generations have probably thought the same.
Imagine trying to explain the internet to Julius Caesar or any citizen of the Roman Empire. They would not have been able to comprehend the basic terms of what you meant.
Next time you think there are no good business ideas, no ideas for your next portrait, or art project, remember that the limitation is within you, not the world around you.
Shut out the distractions and marinate for hours, days, or weeks and the good ideas will come. Start playing and discover what you were once blind to.