Unfortunately for this ask, versioning is at the item level, not the column level. Any changes made to any column will create a new version. And Lists don't offer minor and major versions like Libraries do, so that won't be an option either.
If that's going to be a deal breaker, you could consider this list being a 'behind the scenes' list, create another List based on the structure of the current and then have another workflow that copies items from the current list to the new list when the mission critical columns are edited. May be overkill but not sure how else you can reach the clean version number ask.
