Why didnt Allah put us all in jannah in the first place?!..he could have make us all good..why needed to put us all through these and why to test through belief and fear of unseen??
We are His creation and He can do whatever He wants! If He threw all of us in hell, no one can object to that.
Instead of asking such questions, you should express your submissiveness and humility to Him and beg for salvation from hell!