Generally paid work in comics and novels requires some level of skill, so honestly there are probably easier skills to learn to start making money (computer coding for sure. It sounds intimidating, but it's actually a lot easier and takes a lot shorter time to get good enough at it to earn money than writing or drawing), or much more profitable ones a person without much training or work experience could do (like working in a supermarket or cafe, telemarketing or being a postal worker).
Flatters generally require just some basic image editing software skills, and sometimes people will hire them, but most smaller productions will want somebody with a more general colouring skillset.
Generally flatting or especially colouring, inking or lettering are pretty common jobs in webcomics, but they can be competitive, and often go to people who are pretty decent artists in their own right looking for a way into the industry.
Setting up the 3D models can be a job for a lot of larger modern webcomics, and knowing how to make or manipulate 3D models can have applications in games development, 3D printing and stuff.
Social media management. If I could afford to have somebody handle all my instagram and official twitter posting, I'd totally do it.
Tapas does actually have a jobs page where they sometimes post jobs to apply for. They're often looking for people based in California though.: