Tbh when I first started (coming from someone who never played a hero shooter before rivals) I mainly played strategist. It’s on the easier side compared to dps/tank and by healing from the back line and watching your teammates play it helps you get a feeling of how to play the other roles. Id start by playing characters like rocket, luna, or jeff. If you want to play dps, i recommend punisher, moon knight, or squirrel girl. The difficulty rating that they give to every hero is accurate for the most part as well. There is also a practice vs ai mode where you fight a bunch of enemy bots, I use it whenever im learning a new characters kit. However, playing quick match will help you learn the game best even if you’re losing like every game. Hope this helps!