Hi - It's not super common on the federal level, for example president. Neither Dwight Eisenhower nor George W. Bush had held public office before they were elected. Bill Clinton and Barak Obama had both served in other offices. George HW Bush held a ton of public offices before president so there is no "set" way but it tends to be a trend to be elected to something before serving.
It is much more common at the state level for governor or lt. governor (in those states that have one) to have no prior political experience. Of recent times, say the last 25 years, most members of Congress have been elected to some political office before they were elected but it could have been mayor or state legislator.