[acegopher]

At least for ^ I was always told that the ADM3a terminal keyboard had a HOME key with ~ and ^ on it, which is why ~ means "home directory", and ^ means "home of the line".

[kjellsbells]

Correct on the ADM3a keyboard. In fact the OP site has a pic:

https://www.hillelwayne.com/post/always-more-history/

Whether that explains the use of tilde and caret, I dont know.

[fanf2]

^ for start of line predates the ADM3a