Can Anyone tell me or guide me that why my this design got rejected on themeforest

Presumably, this is only one page of several right e.g. blog post page, donation detail, etc?

The design basics are, with respect, a long way off the standards esp. the typography, hierarchy, and the general concept is not especially premium in terms of the elements, features, and functionality

Especially for a PSD design there is zero room for any design issue and it needs to be very modern and distinct

So can you please suggest me that what can be done to improve this design project, should I only stick to one page or should go for more page e.g. about, blogs, etc.

You need to get a grip on the design basics esp. typogrpahy, use of white space, hierarchy etc. first otherwise you will be creating pages with the same errors