I worked in Inventor for quite a while, and while certainly possible, I'd advice against it. The only way I'd know how to would be making a lot of sketches in parallel planes and swiping, so basically drawing stuff on each plane in the shape it would be at that point. Furthermore, I wouldn't know how to pose it. You could of course make ball joints or something, but there would be gaps if you bend stuff. Maybe it's my lack of Inventor knowledge, but I don't know if it has surface deformation, like when you'd bend a leg or something. I'd advice you giving a try with blender. It's free and created for modelling organic objects with ease. I know it can be frustrating at first, especially coming from CAD like I did, but blender's interface is actually really easy to work with once you know how and it's the best interface I've seen so far in any software.