What is important about the scenario? Goblinoids, or bandits? Could you get the same benefit from having it be a group of humans, elves, goliaths, orcs, kenu or other heritages that launch raids on nearby roads and settlements, explore nearby notable features of the land such as caverns and ruins and often get raided by NPC adventuring parties? What is the unique feature of goblinoids that make this scenario best suited to them? If there is no clean cut answer that you like, is the focus too restrictive?
When we tell the players, "you get to pick from amongst these few options for your PC", it tends to shift the game from being a group game to a game that you're dictating to them. This can happen to different degrees, and is rarely a 'black and white' situation, but when I want to run a scenario campaign, I find it better to keep the scenario loose and then let the players help shape it with their PC choices. Here, you could say the group will start as a group living in a cave lair near a settlement/road that is trying to survive, and their group has historically had to resort to raiding others to do so. Then, let the players figure out how the PCs they want to make fit into the roots of a storyline and where they want to go with the story.