Hi Ma-Frank

As I said, I’m very busy for the next few days, but I just wanted to respond to your essay.

Don’t worry too much about the statistics. Your essay is quite readable. A few steps would make it easier to read: shorter sentences to reduce the average from 16.94 words on average to about 12-15, and some shorter vocab choices.  

Intro

The intro is the weakest part. You have a standardized opening sentence (avoid the words ‘debate,’ ‘issue,’ ‘contentious,’ ‘divisive,’ ‘heated,’ ‘topic,’ ‘topic of discussion,’ etc.) Millions of candidates use these words. Examiners will sigh and ignore them, hoping to find original material.  Your first sentence also has several serious grammatical errors.  Avoid these clichéd openings and write your own.  Throw away the crutches and walk.

The second has no words related to the topic and repeats the first sentence. Eliminate it. Every sentence should have a function related to the topic. 

The third sentence (your thesis) says you will give your opinion. When? Why not give it? Why the suspense? Tell us (the reader) what you are going to tell us, in the intro. Then tell us, in the body. Then tell us, in your conclusion, what you told us. Three steps. Yes it seems repetitive. But it gets the job done, and allows you to show you know a few synonyms and rephrasings. Hammer it home.

Topic sentence in Para Two

I like the first sentence in your second para. Why not use this in your intro?  Or the second one – both are fine. Just forget about ‘debate’ and ‘debates’ and ‘controversial’ and ‘discussed.’  Give us examples. Tell us. Talk about the topic. There’s no requirement to rephrase the question.  Here are a few sentences you could use in your intro:

• Animals and humans today are competing for limited resources. Should our economic and social development be limited in order to prevent animal extinction?
• Animals are suffering today as a result of human growth.
• Animals and man are linked inextricably.
• What we can do to protect the animals and plants we have lived with for millions of years?
• Is animal extinction the price we have to pay for economic growth?
• Sometimes people forget that humans are animals too.
• Today, a small animal in the Andes becomes extinct. Tomorrow, it could be our turn. In this essay, I will explain why we must act to stop the extinction of any more animals.
• Extinction is a natural process. Long before humans, animals either thrived or became extinct, depending on their adaptability. This essay will explain why humans need to come first, before obscure insects or pampered pandas.
• As stewards of the planet, humans have a unique responsibility to other animals. In this essay, I suggest that the greatest mark of our humanity would be to demonstrate our love for our planet and fellow creatures.

Your paragraph two and three are fine.  There are some problem sentences (“Only we possess advanced technologies, sufficient funds and protected captive zones or natural environment, our ecological circle can be protected.”  -  I think this is a run-on, but it needs to be clearer and simpler. )

Conclusion

Your conclusion has one sentence which could be used in a million essays. Even the second one does not mention the keywords or any synonyms.  You wrote

All in all, we should not say which is correct or more reasonable among these two viewpoints.

It's not wrong (this makes it better than your opening sentence in the intro)... but...

Why use a mass-produced sentence like this? Why not make every sentence a part of the topic and the question, in the same way that every fingerprint is a unique identifier of you and every cell a unique record of your DNA?  

It’s easy to make the sentence specific to the topic. Just add the word ‘animal’ to this sentence -  or ‘nature’ or ‘creatures,’ or some other opportunity to show the examiner that not alone do you understand the topic but are capable of writing new, original fresh sentences based on it.

Your paragraphs two and three and the rest of the conclusion show that you can do it. Complete the mission!