You don't have to have a massive DPS pool. General rule of thumb is DPS mains should specialize in one of two roles: hitscan and flex DPS (also called projectile DPS).

Hitscan DPS are aim dependent, they confirm kills, they capitalize on the space that is made for them by their team.

These heroes are widow, tracer, mccree, ashe, soldier, sombra, reaper (and for goats meta zarya).

Flex DPS are also mechanically demanding but since their damage comes from projectile, they are responsible for applying pressure through damage and zoning. They typically involve more game sense and think rather than just raw aiming.

These heroes are genji, hanzo, junkrat, pharah, mei, (and for goats meta brig).

Now that you decide which role you want to specialize, focusing on this hero pool should allow you to use any of the 5-6 heroes in that role to be used any in situation.

You don't have to stay within the role, but understanding the role's responsibility will help you use the heroes within to roles to apply them to any situation.