As somebody who moderates a moderate sized art website, I’d like to add my two cents to the conversation.
There’s a specific set of copyright rules when it comes to the internet that all digital creators must follow. These are called DMCA guidelines, and in short, any image that isn’t marked as royalty free may not be produced and sold for monetary gain without explicitly written permission from the owner of the photo/image. Failure to comply with these rules could actually result in some massive legal repercussions, which is why it’s such a big deal.
Since you don’t appear to be selling these images for profits, you’re technically not doing anything legally wrong because you’re not directly profiting. However, that doesn’t necessarily mean nothing at all was done wrong - the mark was missed since you’re giving away potentially copyrighted pieces - like the man in the brown jacket - away for customers to use, and that is wrong and an infringement on the owner’s intellectual properties. This rings especially true if it was an art scene used for an episode story, and the author of the story is monetarily profiting off of another creators copyrighted work.
Reproducing, tracing, and coloring over existing images/creative works is okay as long as these pieces stay in your possession and aren’t being sold, as nobody’s intellectual properties are being infringed; and tracing is an excellent way to build up muscle memory so that youre comfortable with attempting anatomy for yourself, but again, these practice pieces shouldn’t be given away.
Nobody here is saying that you don’t have talent and saying you’re a thief is a bit harsh, and frankly that’s just not the right way to approach the situation. A much better way is to educate. However, what Line did is a perfect example of how many people in the art community can and will react if they feel as if your artistic integrity isn’t authentic. People won’t stop to think about your feelings, I’ve personally seen huge artists within my community who pulled in thousands a month, lose it all in an instant because of tracing/painting over/heavy referencing. This is why it’s so important that you develop a style of your own without means of heavy referencing, or whatever the case may be in your situation.
TL;DR: I’m sorry your feelings were so badly hurt, and it sucks that it hurt you so badly that you’re quitting art all together, but I’d take this as a learning experience because this is honestly just a small taste of a much larger community.