Oh, it's not so bad. "Person" is a singular countable noun, so it needs a determiner – I'd go with the indefinite article. The reason I didn't understand it was that we "win" a competition, we "beat" or "defeat" people. Your expanded sentence, other than a few typos, is pretty good. "… come into fatigue period…" doesn't really sound natural; I'd say "suffer fatigue." The main problem is the the word "it" in the last part of the sentence had no clear antecedent.

You don't need an article before "ordinary people," but you do need an article before "ordinary person." (either "the ordinary person" or "an ordinary person")

I made up it myself and I've expanded it:"Like ordinary people, professional athletes will eventually come into fatigue period in spite of thier well-developed muscles, nevertheless, it's more than enough to defeat ordinary people in a marathon." And what do you think of the sentence above? And should I add "the" or not if I want to express the general meaning of ordinary people?

I'm afraid your sentence (while more or less grammatically acceptable) doesn't make any sense in English. Is it something you've read, or heard, or made up yourself?