It’s possible but unlikely that the ancient Egyptians were the first American explorers who built the New World pyramids.
True, the New World pyramids were built from 1200 B.C. to the 1500s, slightly overlapping the time when Egyptians were doing the same thing, from 2700 B.C. to 1000 B.C.
However, the styles, building materials, shapes, and functions of the American pyramids were somewhat different from the Egyptian kind. Rather than pointy at the top, the American pyramids were more like layered cakes with a flat top.
The Egyptian pyramids were designed as tombs and monuments; the American ones were used for ceremonies, like human sacrifices, and for military defense.
The oldest mummy in the world was found in Peru, dating from about 8000 B.C. Like the first Egyptian mummies, he was an accident, preserved naturally by dry desert air.
However, here’s a difference between the Egyptians and the prehistoric Native Americans.
In about 2600 B.C., Egyptians began purposefully mummifying bodies; in contrast, the prehistoric Americans never deliberately preserved their dead.