I have no idea how there are conflicting answers, I answer this every day. No matter, one more can't hurt. (Edit: just want to add that I'm not questioning that there are conflicting answers, just expressing my light frustration that they exist still is all)
Short version: you ever play PoE or a Diablo game? Same as that.
Longer version: currently available characters are legacy (standard) characters. On Feb 21, the official 1.0 launch happens. At that point you can create and play both cycle (season) or legacy (standard) characters. Cycle characters are all fresh and are the only characters that can compete on the ladder.
If you don't want to participate in the ladder, don't care about a fresh merchant's guild economy and would like to keep playing your old characters simply keep playing and creating legacy characters and it will be as though nothing has changed for you.
Characters never move between online and offline in either direction.