I would suggest that a similar phrase would be:
**Average Joe**

An excerpt from [Wikipedia's page on the term][1] includes:
>used primarily in North America to refer to a completely average person, typically an average American. It can be used both to give the image of a hypothetical "completely average person"

In the example given in your question, it would be used like:

> The average Joe can solve this problem.

Or some similar phrasings:

>Your average Joe can solve this problem.

>Any average Joe can solve this problem.


Kirt mentions "Joe" in [their answer][2], but I think that specifically an *average* Joe is equivalent.


"Average Joe" is on this list of terms referring to an average person, on which is also found "Tom, Dick, and Harry": https://en.wikipedia.org/wiki/List_of_terms_referring_to_an_average_person


  [1]: https://en.wikipedia.org/wiki/Average_Joe
  [2]: https://ell.stackexchange.com/a/315909/33871