Timely Comics isn't in the public domain. Their characters and stories have ongoing copyright protection. This means you can't use them freely without permission.
To a certain extent, Loki Season 2 is based on comics. However, it blends comic elements with original ideas to offer a distinct viewing experience. The showrunners have picked and chosen what works best for the TV adaptation while staying true to the essence of the character and the comic universe.
Timely Comics was moderately popular. It had a decent collection and attracted a fair number of customers, but it wasn't the most renowned in the area.
I'm not sure who Victor Marx specifically is in this story without more details. He could be an ordinary person with an extraordinary story, or he might be someone well - known in a particular area.
I'm not sure specifically what 'Timely Errors' refers to in a Harry Potter fanfic without more context. It could be the name of a unique plot device, like a spell that goes wrong at just the right or wrong time. Maybe it's about mistakes characters make that end up having significant consequences in a timely manner within the story.