Corrected version:

In this era, most people eat animals to fill their stomachs. 

They want to satisfy their needs, such as clothing and medicine. 

Explanation:  

The phrase "to full their stomachs" is not idiomatic. It should be "to fill their stomachs" instead.

The phrase should be "such as clothing and medicine" to maintain parallelism between the items in the list.

Improved version:

In this era, the consumption of animals for sustenance is widespread. People seek to meet their needs, encompassing both nutrition and other essentials like clothing and medicine.

Corrected version:

 A great many people use animals' bodies to cover themselves. 

In winter, people buy fur clothes to protect themselves from the cold. 

Explanation: 

The subject "A great many people" is plural, so the verb should be in the plural form "use" instead of "uses".

The correct phrase should be "to cover their bodies in winter" to indicate that the fur clothes are used to protect their bodies during the winter season.

Improved version:

A substantial number of individuals utilise animal products to clothe themselves, with fur garments being particularly prevalent during the winter. These garments often feature animal fur as a primary material.

Corrected version:

Fur clothes are usually made from animal fur. 

Many species have become extinct. 

Explanation: 

The possessive form should be "animal bodies" instead of "animal's body" to indicate that the clothes are made from the bodies of animals in general.

Improved version:

Regrettably, numerous species have faced extinction as a consequence of human activities. Additionally, a significant proportion of the population relies on animal consumption as a means of maintaining a balanced and healthy diet.

Corrected version:

A large number of people eat animals to maintain a healthy diet. 

Killing animals and eating them is destroying the animal's ecological cycle. 

This will have significant consequences. 

Explanation: 

The sentence structure is awkward. It can be revised to "Killing animals and eating them destroys the animal's ecological cycle."

The phrase "This will lead major cause" is incomplete and doesn't convey a clear meaning. It requires revision to provide more context and clarity.

Improved version:

The act of slaughtering animals for food disrupts the delicate ecological cycles within which they exist, resulting in far-reaching implications. Consequently, this practice becomes a major contributing factor to environmental degradation.

Corrected version:

Many doctors believe that consuming animals is necessary for maintaining good health.

Animal food contains many bacteria.

Some species consume unhealthy food that is rich in bacteria.

This can cause many problems for non-vegetarian people.

Explanation: 

The statement is inaccurate. While some doctors may support a non-vegetarian diet, it is not accurate to say that "many doctors prefer to eat animals" as a generalisation. 

The possessive form should be "animal food" instead of "animal's food" to indicate that bacteria can be present in the food consumed by animals.

Improved version:

Remarkably, even healthcare professionals advocate for the consumption of animal products to ensure optimal health. However, it is important to acknowledge that animal-based food can harbor a multitude of bacteria, potentially leading to health complications for non-vegetarian individuals.

Corrected version:

Eating animals can disrupt many food chains.

Many species are unable to find their food.

As a result, many species lose their lives.

Some species go extinct.

Improved version:

The widespread consumption of animals disrupts various food chains, impeding the natural availability of sustenance for numerous species. Consequently, this unbalanced ecosystem exacts a heavy toll, with many species perishing and some facing the tragic fate of extinction.

Corrected version:

Furthermore, shoes are also made from animal bodies.

Many people eat fish, chicken, etc., and fish are killed to make medicines.

Many species are in danger and are killed every day.

Explanation:  

The correct form should be "Many species are in danger" to indicate that they are at risk or facing threats.

The term "fishies" is not the correct plural form; it should be "fish." Additionally, the verb form "killing" should be "killed" to maintain correct tense and agreement.

Improved Version!

Furthermore, shoes are crafted using animal hides, which are carefully sourced and processed. A significant number of individuals consume various types of animal products, including fish and poultry. Fish, in particular, are often harvested to extract valuable compounds for medicinal purposes. Numerous species face a perilous existence, being subjected to relentless killings on a daily basis. This constant threat places them in a state of perpetual danger and pushes them closer to the brink of extinction. 

Corrected version: 

Animal bodies are also sold on the market at a high cost.

Nowadays, at parties, people prefer to eat non-vegetarian food to appear fashionable.

In conclusion, I believe that nowadays people prefer to consume animal species for food, clothing, and medicine.

Nowadays, people can not imagine living without consuming animals.

In the modern world, a large number of people enjoy eating non-vegetarian food.

Explanation: 

The possessive form should be "animal bodies" instead of "animal's body" to indicate that animal bodies are sold in the market.

The phrase should be "At parties, people prefer to eat non-vegetarian food to appear fashionable" to convey that non-vegetarian food

Improved version:

Moreover, the utilization of animal bodies extends beyond food and clothing; it encompasses the sale of various products at exorbitant prices. Unfortunately, this commercial demand contributes to the perpetuation of unethical practices and further threatens endangered species.

In contemporary social gatherings, the consumption of non-vegetarian food has become a symbol of fashion and status. Consequently, many individuals opt for such choices to align themselves with prevailing trends and perceptions of sophistication.