I'm glad you knowledge what you're doing but 1st. Did you know that originally "render" meant 3D modeling? So rendering you're doing is actually nothing else, than erasing backgrounds from original pictures.
2nd. I'm glad you don't say they're your own but you still do not have written permission from original artist to use them.
3rd. You don't give original artist any credit.. You only say where picture is from but could you maybe tell me what is the name of artist who drew this:
[link]. I'd like to know. Also may you give me link to their website, since I'm pretty sure they'll have one. Thank you.
If you can't answer 2 simple questions about whose art are you actually rendering, then you aren't giving them any credit. Maybe I would like to see more drawings from this artist but I can't find their names. Giving credit means
giving credit, that means telling artist name and possible website. So peoples will find them easily. So when you render. Find out name of the artist and possible website. Since I'm pretty sure that you won't stop even if I told you then please at least give artists an actual credit.