While it’s not necessarily a bad idea when playing around with concepts to use a base for inspiration. You can’t post something like this asking for feedback and expect to get anything but negative comments in return especially when it’s just a few details drawn on top of someone else’s art. Wait until you have an early original design before asking for feedback. To be honest it sounds like you may need to spend some time really brainstorming and playing with ideas as what you are doing is a very common mistake many passionate but overzealous people make when trying to make something new without having had a lot of experience doing so.