Look... the reality is that most of the problems we have in the world have simple solutions. It turns out a lot of problems actually aren't that complicated - they aren’t rocket science.
Now, that's not to say that it's easy to solve problems. Quite the opposite. The difficult part comes with execution. But that may come in the form of how your solution is implemented, how you build a team and culture, or how you finance and build a business model.
I look at companies like Expensify for inspiration of simple solutions to a simple problem. Expense reports suck, so they made them a pleasure to use.
Or look at Slack: Most people don't like email, Slack cuts down on email and makes offices communicate more efficiently.
Last, look at an app like 1Password. Nobody likes managing passwords and keeping themselves secure. 1Password created an easy way to digitally store passwords and login to your favorite online services.
If you can't explain your business idea simply to a person you pass in the street, chances are you haven't clearly defined the problem (and most likely the solution).
The good news for us all, there are a lot of small problems out there just waiting to be solved.