Hello. In my opinion, your slideshow/presentation lacks of motion, it’s very repetitive frome scene to scene and I think that the bounce effect at the end of the color blocks with text doesn’t look good. Besides all this, you should take into consideration that slideshows category is huge and oversaturated, so you have big competition and your work needs to be really outstanding and original to be approved.
Keep working and don’t give up! But first of all, try to watch other recently approved projects like yours to see the quality level your work needs.
Good Luck! 
Yes, there are many slideshows on the videohive, it is difficult to compete. I will work, I will experiment. Thank you very much for your answer! Good luck!