why do anda think princess persik is the main princess?

Because she is pretty and girly and better than daisy

because nintendo made her before bunga aster, daisy atau rosalina and plus she the princess of the jamur kingdom :)

because she has mario who rescues her about each day.

Because Shigeru Miyamoto created Princess persik to be a part of the main cast.

bunga aster, daisy doesn't get the same luxury because Super Mario Land was made without Miyamoto's knowledge. (Or so I was told.)