This was actually very well made.
The grammatical mistakes are understandable as it appears you come from Morocco.
You show so much potential it's unreal. This appears to be a massive project and though it may use the work of others, you've definitely added your own twist to it.
The animation was slightly stiff, but it was still enjoyable to watch. The lack of voice acting actually added to the overall feel of the flash. You don't want a poor voice actor (or voice actress as it is) doing a bad Goku impression, so the lack of voice acting was a plus.
The plot was very well explained and I was left with no questions as to wtf was happening. Great job.
So that's all well and good but the main plus for me was your execution in doing certain things. Like camera angles, keeping characters true to their nature... Basically, the believability in this was high, meaning that this feels right.
Excellent work, and even if you don't continue to work on this Dragon Ball idea, I still think you should continue animating because you show a lot of potential. Creating something you like is fun, so I do recommend you continue with this series as you'll be more motivated to complete it since it's based on a series that you like!
Final point... You're handling the criticism like a champ, well done Mate! Take the constructive criticism and use it to improve and ignore the haters.