How does levelling work?

Freelancers are Pilots. Levelling occurs with your Pilot. The Javelin exosuits do not have a level progression. There are 4 Javelins. You start with the Ranger Javelin. Once you hit Level 5, you can choose your next Javelin. As you progress, you can select your preferred choice at each level gate. Enemies that spawn in-game/activities you engage are based on your personal pilot level.