I think your originality and imagination is fantastic and that you can make tangible your creativity is even more fantastic! I can copy fairly accurately but I lack both imagination and originality so I really admire your work.
I especially like the skull (and don't consider it incomplete at all) and I suggest the idea of the tree trunk with arms and hands could be taken and re-done more detailedly and bigger - more arms, more hands etc. Take your time over it and do a complete picture - and then maybe get reproductions done and market them? Excellent talent - keep up the good work!