The OP seems to raise two questions: (1) is there much objective evidence that the Israelites were ever slaves in Egypt? and (2) if there isn’t, do most scholars therefore conclude that the story of their bondage is a myth?
I can’t answer the second question except to say that some scholars–including some faithful Jews and Christians believe that the Jews were never really slaves in Egypt. Whether they constitute a majority, I don’t know. Possibly nobody has a good feel for this.
As for the first question, of whether there is much objective evidence to support the idea that they were ever slaves in Egypt, the answer is far more certain. No: there is no good evidence that they were.
There was a Pharoah in the 13th Century B. C. named Merneptah. A kind of memorial pillar has been found which commemorates his victory over a nomadic people who are widely taken to have been the Israelites. Some historians are not certain about this identification.
In any case, the memorial seems to say that The Egyptians wiped them out. Then again, totalitarian governments have a way of overstating things: remember when the Iraqi government was saying they still were in control of the Baghdad Airport and were winning the war?
I recall reading once that there is a mention in an Egyptian document–apparently a kind of summary report or briefing paper from an official in an outlying province–that there sure seem to be a lot fewer foreign slaves around than there used to be. If this refers to the Israelites, it seems to suggest that there was no mass Exodus, but possibly a gradual escape, possibly along the lines of the Underground Railroad.
There is no record of the plagues. There is no uniform agreement on where the Israelites would have crossed a body of water, or where Mt. Sinai is.
The Ark of the Covenant might serve as objective evidence, as it was built during the time of wandering in the desert, and there should be a pot of manna and the tablets of the Ten Commandments with it. Only nobody seems too sure of what happened to it; it was hidden to prevent its capture by an invading army, and then stayed hidden. There seems to be a widespread belief among archeologists that the Ark may still be stashed in a cave somewhere, and that possibly the people who knew where it was were all killed or captured in subsequent fighting.
There is an Orthodox church in Ethiopia which claims to have it; supposedly it was brought to Ethiopia by the Queen of Sheba’s son who, IIRC, was her love child by King Solomon. Unfortunately, there appears to be even less evidence for any of this story than there is for the story in Exodus.
The life of Moses seems to be very similar to that of a legendary pagan hero named Mises, who, IIRC, likewise was found and adopted by royalty at the contrivance of his mother. This seems to have been a popular motif in ancient literature; something of the same kind also happened to the Greek hero Perseus.
Maybe the absence of evidence does not refute the possibility of the story in Exodus so much as it points up a problem with history, and especially ancient history, generally: evidence is often spotty, and where it exists, it is often questionable.
The lives of Roman Catholic saints serve as a good illustration. During the Third Century A. D., a time considerably more recent than the era in which the Exodus would have taken place, there supposedly lived St. Filomina, St. Christopher, and St. Perpetua.
In 1802 some construction workers in Rome inadvertently broke open an area of catacombs which had not been previously discovered. In one of the tunnels was a tomb built into a wall. Scattered on the ground in front of it were tiles which had been affixed to the wall to provide an inscription. When the tiles were put in order, they indicated that this tomb–which had apparently been built with great care–was the final resting place of the martyr St. Filomina.
Prior to this nobody had heard of a St. Filomina, or, for that matter, anybody with the name Filomina. For a time there was a great vogue of interest in her and, to this day, Irish and Italian girls are sometimes inflicted with this name. (My maternal aunt was named Mary Filomina until she turned 21 and promptly petitioned the court to change her name to Mary Rose).
After the tiles had been exhibited for a long time in a museum, somebody noticed something unususal: they could be rearranged to form another, entirely plausible and grammatical inscription. It was a loving tribute to a wife by the husband who had survived her, and said nothing about anyone named Filomina or anything about martyrdom. It was apparently simlar to inscriptions which had been found before. The Roman Catholic Church issued a statement that there was nothing to support the idea that there had ever been anyone named St. Filomina.
It is sometimes said that the Church has also denied the existence of St. Christopher. While his feast day was abolished, the truth is a little more complicated. What the Church actually did was say that the question of his existence is a toss-up.
The only story known about St. Christopher is the account of his conversion. Christopher (which means “bearer of Christ”), was a soldier of fortune and an all-round mean son of a bitch. One night at a drunken revel the tyrant for whom he worked boasted that he wasn’t afraid of anything or anyone except The Devil.
Christopher had never heard of this “Devil” guy before, but he figured that since he was such a tough hombre, he wanted to work for him instead of a ruler who was scared of him. So he went searching for the Devil.
It was a hard search; he could find places where there had been crimes and disasters and people said he had been there and wrought destruction, but nobody could ever tell him where to find him now. One day as he was crossing a desert, The Devil somehow came up behind him, riding on a black camel. He told Christopher that he knew he had been looking for him, and told him they were going to do some serious damage together, which Christopher thought was pretty cool.
Then they passed a shrine out in the desert, and The Devil acted scared of it. It was a shrine to Jesus, and The Devil acted sort of the way vampires do in horror movies when he saw a cross. Christopher asked him why, and The Devil admitted that Jesus scared him.
So now Christopher went looking for Jesus, and with about as much luck as when he had been searching for The Devil. One day he came to a rushing river, and there was a little boy who said he wanted to cross to the other side. Maybe Christopher was mellowing because his searches had tired him out; he offered to carry the little boy on his shoulders as he waded the river. Just as happened when Jason carried the goddess Athena on his back while she was disquised as an old woman, it was a much harder job than he expected, and when they got to the other side he said he hadn’t expected the boy to be so heavy.
The little boy replied that this was because while Christopher was carrying him on his shoulders, the little boy had been carrying the world on his shoulders. Christopher realized that he was in the presence of his Savior, and, at Jesus’ bidding, went forth to do live an exemplary life.
This is a very sweet fairy tale, and it is the whole of what is known of St. Christopher. Does this mean, then, that he is just a character in a story? Well, supposed that in about two thousand years all anyone knows about Davy Crockett is that he “whupped him a bar when he was only three”. What, if anything, will historians conclude?
This leaves St. Perpetua. She was a young woman with an upper class Roman upbringing who was imprisoned for a stretch before being executed on account of her faith. She was not thrown to the lions, but to a cow. After the first time she was trampled, she got up, bloody and mangled and asked when the heifer was going to be released; evidently she was in shock, but some people regarded this as a miracle. She was killed in the second attack.
The literal existence of St. Perpetua is not doubted. She was a voluminous diarist who recorded her dreams and the day-to-day events of her life, and historians can even account for what she ate on particular day. In fact, she is a source for information about ordinary daily life in her times. It is from her, for instance, that we know that the early Christians used to hope to be thrown to leopards, as that was said to be the fastest and least painfull way to go.
Back in the 19th Century some scholars had a fanciful notion that the pyramids at Giza might be the storehouses Joseph ordered built fduring the seven years of plenty. I don’t believe there is any assertion in the Bible that the Israelites built the pyramids; only that they did slave construction labor.