The speed of light number is probably a coincidence. Although it does pass through the pyramid, it also passes through many other monuments. This line passes slightly North of where it is supposed to according to ufologists, it is not the apex of the pyramid. If you insist on including seven decimal places for a degree of latitude, it is possible to draw 20,000 other lines through the pyramid, none of which are interesting numbers.
It is very easy to make a line of stars line up with a line on earth, everything lines up with some stars somewhere
It is not very difficult to find true north by looking at the night sky and finding the pole star.
We know that the Egyptians were highly skilled at astronomy and mathematics from examining ancient texts.
The ancient Egyptian interest in astronomy does not imply they must have met aliens.
The speed of light number is a coincidence, and not an impressive one. We know from written evidence that the Egyptians were knowledgeable about mathematics and astronomy. The is no evidence for the existence of ancient aliens, they are not a plausible alternative explanation.