regular expression syntax

i'm wondering why * means 0 or more matches and + means 1 or more matches

i know this notation comes from formal language work and math (kleene star) but is there any reason * and + were chosen? or are they just random symbols?

Why is * for complex conjugates? Why is a bar over x indicate that x is a mean of other x's?

Why is the kanji for house a roof over a pig?