In casual German, “an average American” is usually expressed as:

  • „der Durchschnitts‑Amerikaner“ (for a man)
  • „die Durchschnitts‑Amerikanerin“ (for a woman)

This literally means “the average American” and matches the nuance you’d use in English when talking about a typical or “everyday” American in a relaxed way.

Extra notes for context

  • If you just want “American” in a casual context, Germans often say „Amerikaner“ / „Amerikanerin“ (e.g., „Er ist ein Amerikaner.“).
  • For a slightly more generic, almost slang‑y feel you can lean into „typischer Amerikaner“ (“typical American”), which is natural in conversation and on forums.

So in a quick chat, you could say something like:

  • „Ich denke eher an den Durchschnitts‑Amerikaner, nicht an die Extremfälle.“
    ≈ “I’m thinking more of the average American, not the extremes.”

Information gathered from public forums or data available on the internet and portrayed here.