There really isn’t any evidence that Moses existed. Historians generally agree that both Jesus and Muhammad are based on people that almost certainly existed, although the accounts we have of the details of their lives are not contemporaneous, so their accuracy is very debatable. The men we call Jesus and Muhammad from religious texts almost certainly differ in some way from the real people that inspired the writings, but we don’t know how or by how much they differ.

One big difference here is that Moses would have lived at least 1200 years before Jesus did. This is long before any paper writings existed, and not too many papyrus writings have survived since then. So in trying to confirm Moses’ existence, historians have the problem that not much documentation exists from this time period.

Consider that the kings of Israel, David and Solomon, are believed to have reigned a few hundred years after Moses, but there’s no archaeological evidence at all that they reigned over a mighty empire like the Old Testament describes. The best information that we have is that the region was mostly inhabited by villages instead. Many historians don’t believe that David or Solomon existed either.

One major argument against the historical Moses is that we have no evidence that the events of the Book of Exodus occurred. The most meticulous record-keepers in the region at the time were the Egyptians. Despite the fact that we know they kept records of who owned slaves and how many, there’s no indication that they kept the Israelites captive anywhere in Egypt. The Egyptians went out of their way to document which peoples they conquered over the centuries, but don’t mention dragging all of the Hebrews to Egypt and keeping them there for many years, which is an odd thing to leave out. No captivity means no Exodus. If there was no Exodus of the Israelites from Egypt to the area we now call Israel and Palestine, then who would Moses even be? Just some shepherd tending his flock who happens to have the same name?

It’s important to remember that the Torah was not compiled until hundreds of years after the events that it describes, with much - or maybe most - of it not written down at all until then. So the decisions about which versions of those stories to include in the scriptures were made by people who didn’t witness any of the events or even meet anyone who could have. That doesn’t mean that Moses never existed. (We can’t really prove a negative, after all.) But it does mean that we can’t really substantiate any of the events that the Old Testament describes Moses as participating in. As often happens, being sure that Moses was real is almost entirely a matter of faith.