You don’t need to play seasons, you don’t even need to play seasons in day 1. You can join whenever you feel like you want to start a new character.

Seasons aren’t a big deal, they’re usually just to offer people an excuse to keep making new characters, to give them a small reason to (like a new mechanic or new build options, items, etc)

If you’re not done with your original character, just keep playing it. You’re not missing out on anything

The fact that season are starting so early into the lifespan of the game is a little odd. Most players aren’t finished with their first character yet