yeah. olimar, louie and the other captains are the size of a quarter, pikmin are the size of a dime. the mireclops is on record as being the biggest enemy in the game. the man-at-legs has infinite ammo. louie has dominion over all bugs, so he could get the poison dweevil to poison your food. the armored canon beatle has homing boulders, but they are theorized to hone in on certain metals present in space suits. the bulborb larva are insanely weak, they take one punch to kill. the burrowing snagret would be startling, but easy to deal with at human size. the bulbears can infinitely resurrect; which would be annoying; so you have to cook and eat them. you could stomp on the wollywogs and the bearded amprats. you can eat every enemy here besides louie, so yeah; a human sized human could defeat all of these without much difficulty.
being olimar size would be a different story.