I don't like it that you have been downvoted. Your objections are valid ones, because dogmatic biases exist. However, I think that such a question does deserve more than a simple answer. (And as an aside, I find it a little amusing that you were refering to a theologian to make your point.) So let me try this:

When we talk about a person we have been trained to apply implicit frameworks, which are typically quite vague, what gives us confidence that a certain character really existed and is related in such and such a way to what is said about this person. Saying that someone is a historical person means that we have a canonical body of knowledge related to that "person" that is considered (more or less!) being historically valid. For a mythical person the opposite is true: we have a canonical body of knowledge related to that "person" that is considered (more or less!) being ficitional. Some canonical truth about a historical person might turn out to be false; but such a discovery might not make this person suddenly fictional. Or we might discover that some narrative about a fictional character is rooted in an historic event; but this does not make this fictional character suddenly a historic person.

However, this contrast between a historical and a fictional person marks only the ends of a spectrum. Many characters from the past are somewhere in between. You do not need to go back to antiquity for some interesting cases. Take for example the so-called Shakespeare authorship question,[1] which might be summarized with the bon mont, that the works of Shakespeare have not been written by Shakespeare but by another person with the same name. But all joking aside, when discussing ancient characters which have a large fictional text corpus around them, scholarship typically differentiates between a historical X and a fictional X. Among scholars this difference is usually only made explicit, when one is contrasting the two, and left to the context if not, because it goes without saying. So we speak for example of the historical Socrates in contrast to the Platonic Socrates (as a character in Plato's dialogues). And of course there is a debate which features of the Platonic Socrates might be ascribed to the historical Socrates and which not. (And the closest sources about Socrates are from his biased desciples Platon and Xenophon -- aside from some jokes of Aristophanes.)

Regarding Jesus, a similar distinction makes sense, between a historical Jesus and the Jesus of the gospels (and the Jesus of other sources). In its modern form this distinction has a very long and intense research history starting in the 18th century.[2] The complexity of this research history shows that it is all but easy to identify the historic Jesus behind the sources, but that we have nevertheless so much evidence, that some historic person takes shape behind the narratives. However, there is almost no substantial agreement about the individual features of the historical Jesus other than that he was a male that was cruxified during the reign of emperor Tiberus in Jerusalem. I personally think that much more can be said with good reason, but any other claim is at least a tiny bit dubious.

In contrast, when we focus on characters like king David, Salomon, Josua or Moses there exist next to nothing that links their biographies from the bible to external evidence and a lot of evidence that contradicts the details. This does not mean that no connections can be made between these stories and some presumed historical events backed by other evidence. But this connection is not strong than, for example, the connection between the legend of king Arthur and the history of the dark ages and late Roman Britain and Brittany.

>> As an archeologist, ...

Biographical footnote: I studied philosophy, but had to chose a so-called "minor subject" that was (protestant) theology, which was methodically quite neutral. i.e. biblical sources were treated like any other historical source and being sensitive to once own potential biases was part of the methodology. In practice, this meant that there was a lively exchange between the theological department, historians, papyrologists, egyptologists, classical archaeology, philology etc. You were even required to take a certain amount of courses in other departments. As being a secularised student myself, it was no problem at all to study theology. I would estimate that only about half of the theology students at that time were "observant" Christians in the stricter sense.

[1] See: https://en.wikipedia.org/wiki/Shakespeare_authorship_questio...

[2] For an overview see: https://en.wikipedia.org/wiki/Quest_for_the_historical_Jesus