meaning of 一人じゃ


I'm familiar with 一人じゃない, but I'm not sure what 一人じゃ means. Is it a contracted
version?  

I found the word in this context below:  

> 一人じゃ運べそうもないから、手伝ってくれる？  
>  _(Since it seems like I'm unable to carry it by myself, could you help
> me?)_




1人じゃない = 1人ではありません。 Consider that the negative form of “です" is “ではありません",which
can also be “じゃありません" So I think “じゃ” is used as a simple form of"では".




1人じゃない = 1人ではありません。 Consider that the negative form of “です" is “ではありません",which
can also be “じゃありません" So I think “じゃ” is used as a simple form of"では".

