i think its ok to copy it when you just use the original image as inspiration. Cause you can even do fanrts without braking any laws, right? So why not redesign a model.
There was even someone who made Ifrit and Tidus from final fantasy, and as long as you say the idea is not from you and when you dont sell it, its totally okay.

but jetpack is right anywayx, do your own models, it gives your game an unique style.