Casting,why can the king move 2 spaces?

Just why can a king move two spaces

This is all I could find here on chess.com, but I bet you could google it and find something on the history...

Castling only involves the king and the rook (no other chess pieces), and it is believed that it was invented around the 1500s in order to speed up the game.

I guess it mimics a king running for shelter from a possible attack.

Once you have a rule about castling, the king has to move at least 2 squares for king-side castling. Making the move the same for queen-side seems most logical.

Of course, I recently read that free castling used to be a variation, so two squares may be more modern standard.

It is a very weird rule though

The king runs to safety behind a wall of pawns and behind a rook. It makes perfect sense.

(At least to me)

ask the guy who invented chess a thousand or so years ago

Chess was invented by a guy name Chester. This is why there is no opening called The Chester or a Chester variation. 

amazing nolej

I only recently learned about this rule and how to do it. I always wondered how it worked but no one ever taught me. I figured out when I found this site. It's been so very helpful.

The queen was given more power to speed up the game. To counteract that castling was added. It was unnecessary as recent research shows: even no castling chess is a draw. 

#16
Castling as we know it now was introduced in 1620 after the queen got more power in the 16th century.
About no castling chess, see figure 2b of this paper
https://arxiv.org/pdf/2009.04374.pdf 

If I invented chess castling would not have castling

I created the account name with the words "fiend" and "fundamental".

because when you use casting, all the magic and hidden powers get unleashed..
First you need to understand that selling your soul to the devil is a bad thing.
Secondly, casting is very dangerous, you can cast a spell that will bounce back to you.