Pony cmc are clearly elementary school kids but the human cmc are in middle school, while the mane 6 are shown to be young adults at the very start of the series. Rarity owns a business, Pinkie rents a place, Rainbow Dash was probably middle management on the weather team by the way she acted to the others on the team and later join the military, Fluttershy found it pathetic that her baby brother wanted to move back in with their parents without holding down a job. Plus pony Big Mac by all accounts seem to be the same age as Cheerilee but human Big Mac is a high school student and Cheerilee is a teacher there. So no the pony ages do not match up with their human counterparts, which in a make sense.