Does the Moses you envision lead a group out of Egypt?
Does he lead a group that lives outside Judea/Israel for an extended period of time?
Does he have a brother named Aaron?
Do you have some thoughts about whether he died before entering Judea/Israel?
Do you believe there was a Joshua?
What I'm getting at here is that so far I'm clear that you think there was an HM but I'm wondering whether your views are so vague about the guy that you don't really believe we know enough about him to make a good guess as to whether substantial elements of the biblical story have a factual foundation.
I think it's more likely that there was a historical Moses than that there was not.
If there was not a historical Moses, then we have to assume that the person who did promulgate the first code of law among the Hebrews, who would have had to have been a very powerful person within that society, decided not to claim that God gave him the law, but rather that God gave the law to a historical hero or folk hero.
You might say, well, that was to legitimize it.
But that makes very little sense for several reasons.
First, it's already legitimized by God and by this ruler's own power.
Second, we have no historical parallels for this, and it doesn't make a lot of sense psychologically.
Third, if Moses were already a figure to which such things could be attributed, why does no one protest (especially the Aaronites) that the new stories were not legitimate, or try to claim that it was their guy instead who recieved the law? Attempting to attribute the law to a figure from the past whom no one believed established the law already would be very difficult to do. It would not increase legitimacy, but rather undermine it.
So the legitimacy angle just doesn't pan out.
I also don't buy the "origins story" angle -- that there was a desire to trace origins to Egypt for clout -- because neither the Mushites nor Aaronites (the Levitical groups chiefly responsible for these Biblical texts) trace origins back to Egypt, but rather to Mesopotamia and Syria (both via competing Abraham stories). And in any case, the stories serve to glorify the Hebrews over Egypt, not to glorify any Egyptian roots.
If the HM hypothesis is correct -- and the evidence is so sketchy that I think we have to stop at hypothesis -- then I think you have to also have a historical Aaron hypothesis, although there's no reason to think they were brothers.
First of all, only one group of authors identify them as brothers, and secondly, genealogies in Biblical literature do not serve to identify actual family lines, but rather to outline and solidify the current alliances and enmities of the time of the authors.
Under this hypothesis, Moses is the leader of an elite group of warrior priests who came up from Sinai and unified the Hebrew Tribes after making a pact with Ephraim and Judah to displace Benjamin, and possibly introduced circumcision as well as Yahwism as the state religion.
This would be a very effective combination of techniques for solidifying power and control.
According to this view, the Levites were never slaves in Egypt. They were most likely captive elites who retained rank within Egypt, perhaps over generations. Within Egypt, they would have been of little note, but once out on their own and reunited with their ancestral tribes, what they learned in Egypt would have made them top dogs.
If this view is at all accurate, Moses certainly did not die before entering Canaan, and that story is later Aaronite propaganda.
The thing about these sections of the Bible is that they're like... well, it's as if someone a few centuries now were to weave together commentary from Bill O'Reilly and Keith Olbermann to make a single history of the George W. Bush and Obama presidencies. You get Aaron-bashing from the Mushites, and Moses-bashing from the Aaronites.
But some things cannot be spun. Like boulders in the river, there are facts that everyone agrees upon. And there are also myths which serve the purposes of both sides, and those get perpetuated, too (such as various types of pro-America propaganda).
The Moses-as-lawgiver trope appears to be -- can't say it is, but it seems to be -- a boulder-in-the-river fact.
On the other hand, the exodus story serves the purposes of all the Levitical groups -- Mushites from Shiloh, Mushites from the northern and southern temples in Israel after the disposition of the Shiloans, Zadokite Aaronites, and non-Zadokite Aaronites -- by claiming that it was they who delivered Israel from bondage and don't you ever forget it!
No doubt, the exodus story we have today is many generations post-Moses and post-Aaron, assuming they were historical persons and that Moses did write the first Hebrew code of law. That story could not have gotten traction in their own day.
Joshua is also, in my opinion, most likely a historical figure, a warrior king who conquered some of the other city-states in Canaan. But the various conquest stories later told and written about him, especially the version which have him always victorious, are dubious.
It's difficult to find straightforward military accounts in these sections of the Bible. But there are some. For example, we have 3 accounts of the destruction of the cities of the plain (including Sodom and Gomorrah). Two of them claim that God destroyed the cities, but in the third (from a source whose origins are now lost) they are destroyed in a war.
Anyway, the various stories about Moses serve various purposes. His birth story is meant to explain his Egyptian origins in a satisfying way while asserting a set of providential portents and so on.
The various law-receiving stories are necessary because the Law wasn't like the US Constitution, it couldn't simply be amended, so subsequent leaders who wanted to add to it had to expand on the story.
Much of the remaining tales are competing Mushite and Aaronite propaganda, either glorifying Moses and bashing Aaron, or glorifying Aaron and bashing Moses as much as one could get away with.
ETA: Although the Levites may have begun as warrior-priests, at some point rather early on they lost their military role and continued to hold power as co-regents with the military rulers. It worked for them for a thousand years. Not bad.
Plausible really doesn't mean anything, so I'll happily grant that whatever anyone wants to believe, is plausible to them.