One of my significant motivational drivers is that I am a qualified member of your program in terms of professional knowledge.

What you write is grammatically correct, but illogical. You can't be motivated by already being qualified.

FA four-year diligent study will provide me with a cornerstone of study programme will provide a solid foundation into understanding British and American culture.

"diligent" seems out of place. I don't think "cornerstone" ("an important quality or feature on which a particular thing depends or is based") is used correctly here---what's the quality or feature?

Another key factor involved is that I prevail onexcel at reflection, summarization, and innovation, which is underpinned by the fact thatas demonstrated by how I once summarized an effective and convenient method of memorizing English words witthrough the combination of their roots and affix under thees, in the context of lexicology context.

"prevail" is not the correct word---this is when you have a competition, and only the winner prevails.

The most worthy of mention is that I alsoMost notably, I have stroiven to improve my competitiveness in a variety of social practices andsettings and during internships.

What you originally wrote ("The most worthy of mention") sounds arrogant. (If you say "strove" in past tense, it implies you're not doing it any more.)

"social practices" refers to things like eating habits, good manners, etc. (and ill-matched to "competitiveness")... I feel like "social settings" is more likely correct

Adducing several concreteFor instances, I once represented Guoda (Tianjin) Science and Technology Development Co., Ltd when attendedat the China Import and Export Fair, known as China’s largest comprehensive international trade fair, during which my show ranked the second in thefor English live streaming in English.

"Adducing several concrete instances" <--- writing like this is annoying, as if you're deliberately trying to confuse the reader: you should write like a human is going to read it, and you want them to understand what you have to say. Perhaps you might impress your teacher into giving you higher marks, but it'll likely backfire and annoy native English speakers.

BesidesMoreover, my experiences as a member of manyultiple school clubs and an organizer in arrangingof the Star of Outlook English Talent Competition have greatly enriched my college life and also helped to improve my communication and organizational skills.

In general, I encourage preferring "Moreover, ..." over "Besides, ..." in formal writing. While they're synonyms, they're not used in the same way.

Usually when we say "[blah]. Besides, [foo]." we tend to think of "[blah]" as less significant: there's a change in the speaker's thought process, where we realize "[foo]" is true, which overrides any discussion of "[blah]".

Good: "I don't want to go out to dinner with you. Besides, I have a boyfriend."

Bad: "I washed my face today. Besides, I washed my face yesterday too." (In fact, I feel this example is just plain wrong.)

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"organizer in arranging" is like saying "organizer in organizing"

Likewise, I possess great leadership capability withI additionally have significant leadership experience as a deputy store manager of a makeup shop.

What you wrote is technically correct, but sounds overconfident and off-putting.

Over the course ofDuring my tenure, I led the whole staffour sales team to achieve first place in terms of sales volume.

"the whole staff" sounds weird to me...

I also putilized my teamwork skills to good use as a sales assistant of Kenji department in Decathlon.

What you wrote is correct, but wordy. (Also, consider the possibility that the reader does not know what Decathlon is.)

I assisted the manager and solved many challenging problems witthrough time management principles,, via establishing a clear division of work and with the whole-hearted cooperation of every team member.

It needs to be rephrased since you cannot take full credit for "the whole-hearted cooperation of every team member"

During the course, I was rated the Outstanding Member of Staff and won the Service Star withfor my excellent performance.