Firstly, Jelly is very sticky, if we had 2 Heads, Jelly-like & Human-like, both heads might remain stuck to each other!
Secondly, flies love Jelly, if we had 2 Heads, Jelly-like & Human-like, flies may not leave us alone!
Thirdly, Jelly is very tasty, if we had 2 Heads, Jelly-like & Human-like, our pet dog may not stop licking our Jelly-like head!
Lastly, Jelly can melt very fast due to heat, if we had 2 Heads, Jelly-like & Human-like, our Jelly-like head may melt as soon as we step outside!