No one's claiming all the records just disappeared. First off, as I mentioned in the post you quoted according to the bible god sent hail strong enough to smash trees upon Egypt. This hell could have easily destroyed many tablets, to add to that Egypt was conquered and fought many wars and went through many kings throughout the generations these records could have easily been lost. You act as if they have records perfectly stored in filing cabinets where no one can get to them. One king may value record keeping, another may not, one may seek to destroy the history of a previous king in order to easily build his own legacy or control the masses.
I never claimed that the Jews built the pyramids, I personally don't know who built them, I do however know there are many hypothesis out there which range drastically in opinion. People can't even agree on the color of the Egyptians let alone who exactly built the pyramids or what their use or purpose was for.
I do suggest listening to the audio book of Exodus it's on youtube, I'll post it below. That being said, the Jews did not just wander about entire time. They fought in wars and battles, defeated a few nations and settled in some of their territory, this happened because they were faithless to God and did not heed His word. You also have to realize the Israelites had already tried to enter into the land once and been defeated, without the lord on their side they stood no chance of winning.
