Most accepted theories on the construction of the pyramids are based on the idea that it was built by moving huge stones from a quarry and dragging and lifting them into place. The disagreements center on the method by which the stones were conveyed and placed. Regardless, there were likely many ladders involved in its construction, such as on this level.
This level is mostly a run around. Picking up the treasure while avoiding mummies is not so hard - but getting treasure away from the mummies is a much harder task. The three-wide stone platform is a useful killing field, although you'll have to run around a bit to get the mummies carrying treasure to line up properly. Note also that the middle block of this platform is a fall-through block.
And once you've gotten all the treasure, you'll need to cross over to the escape ladder. One way to do this is to kill a mummy and cross over on its back when the mummy crosses from the escape ladder to the main pyramid.
