(The above rendering comes from the RJPS translation, an adaptation of the NJPS translation. Before accounting for this rendering, I will analyze the plain sense of the Hebrew term containing אִישׁ, by employing a situation-oriented construal as outlined in this introduction, pp. 11–16.)
In the schematic question clause הֲבָא עוֹד הֲלֹם אִישׁ, the term אִישׁ refers to a participant in the present situational context, in terms of that situation. Thus it is playing one of its classic discourse roles.
Because אִישׁ is not marked as definite, one might be tempted to construe it non-referentially (non-specifically), as akin to an indefinite pronoun. However, arguably a nonspecific question about the meeting’s attendees would have been framed differently, using the pronoun מִי (as in Deut 20:5–8; Judg 21:5; 1 Sam 30:24; Zech 4:10). Furthermore, pragmatically speaking, the question must be a pointed one. It goes without saying that the presumptive king has just missed his big entrance, and that everyone has been anxiously trying to find him. Surely the questioner is asking about Saul—and Saul alone. Therefore the intended reference must be situationally unique. In such a discourse context, the referring expression does not need to be either marked as definite or more explicit, in order to point straight to Saul. And this construal is immediately confirmed by the wording of the answer, which presupposes that the reference was indeed unique—and identifiable.
Here it is not surprising that the Septuagint employed a definite article in its rendering of the referring expression: εἰ ἔρχεται ἐνταῦθα ὁ ἀνὴρ ἐνταῦθα.
As for rendering into English, the NJPS ‘Has anyone else come here?’ seems to miss the mark. (KJV and NRSV rendered with a definite article.) I therefore offer a footnote with an alternative rendering that reflects the above considerations.