your design is too basic bad colors. no spacing, bad typography, padding&margins, etc
you need practice more for approved themeforest.
What can I do to improve my design? Any suggestions
you need select better colors, you gan search google, need to size same tp and bottom slider, all sections and pages, need more to size padding/margin, you need improvements typography for example css: line-height: 1.8, font-size: 15px or also change other font, etc.
That’s highly appreciated @JeriTeam
Your help means a lot to me.