easy to find. type in pico de gallo on wikipedia.com i checked and all the info you need pops up.

It is a type of salsa made with fresh vegetables and translated means “Beak of the Rooster”, it would be hard to pinpoint the exact creator as some things are made and past on generation down, so it is not Caesar salad or other foods were some one took a few leftovers or quickly made something to feed a few customers, some things are just made and no one take credit for them like ketchup, soya sauce, mustard and pickles they were just made and not one is really named for there invention.

Pico de gallo is a type of sauce that uses fresh tomatoes, onions, peppers. It was not invented by a particular person. It just evolved as a food tradition. Kind of like asking “who invented gravy?”
or “who invented salad?”

Here’s a little more info:

well im mexican,and
pico de gallo can mean many things
like fruit salad with peper and lemon juice
also cucumbers salad with salt hot sauce and lemon juice
or any fruit sliced and prepared that way lemon juice and hot sauce
but some how people tyhings that pico de gallo is only tomatoes,onion and pepper chopped and lemon juice and salt,
pico de gallo for me is any fresh fruit chopped or sliced and served with hot sauce,salt and lemon juice(mango,papaya,are my favorites but pineapple is delicius too,cucumber i love it.
as of matter of fact im doing one right now,with mango and oranges