Overall, I find that I like your organization, but there are some things I would change and a few I would rethink.
In your essay on David Almond's novel, Skellig, the things I would change are some of your word choices and/or phrases. This is a tough call: I have taught 9th grade Honors English for several years. Not having you in class, I cannot fairly say that your choices are wrong, and they may be examples of writing that are very much in character with your writing. If this is the case, this concern would not apply to you, but to others who may see this answer.
It is important to write in your own voice, rather than trying to sound more sophisticated by using terms that are not generally a part of your vocabulary. If you do this, a teacher might believe you had help or cheated in some way. However, with this said, if this is your style, it will not cause any concern on the part of your teacher. You be the final judge.
My first reaction came with the use of "cogent" in the first paragraph. Also in the first paragraph is the use of the phrase: "consistency, understanding and value." This phrase seems rather vague to me. If you do not address these specific aspects in the rest of your essay, they really are not necessary.
The last sentence of the first paragraph raises some questions:
Three key themes of the text that present enduring significance are the use of wings, the cruelty and beauty of nature, and faith and love.
First, add a comma after "nature" for clarity; then, a theme can be "the repetition of a meaningful element," but I personally struggle with one word being a theme. The other two aspects of a theme are:
(1) the abstract concept explored in a literary work; (2) frequently recurring ideas, such as enjoy-life while-you-can...
I would relate to the aspect of flying: "flying is literally what an animal does with wings, but figuratively, it can also refer to one's elevated spirit." Birds and angels fly; your symbolic details are very good. However, what about Michael and Mina, who learn to fly without wings, but whose hearts also learn to soar in showing love and kindness to another being?
The last thing in the first paragraph talks about the cruelty of nature: see notes for third paragraph!!!
Second paragraph: "whose name remains unidentified" should read "who remains nameless" because she is identified as his mom.
(Every time you write the novel's title—not the creature's name—you need to italicize it: this is only done for novels, plays, movies, etc., NOT short stories, poems, songs—which go in quotation marks).
At the end of the second paragraph, "Due to these, wings..." should be replaced with "Wings..." and the end of the line would be better with "...the integrity of the plot development."
Third paragraph: in the first line, it should read "demonstrates the text's..." In your supporting information about nature, the parent birds are not cruel in protecting their children. We could say, "Nature is beautiful, but in the harsh light of reality, the survival of animals depends on their need to kill and eat other animals." I would go with "harsh," not "cruel." I don't think "Owl" should be capitalized—check it in the book. In the fourth sentence, remove "and their own egocentric purposes." It's not accurate. And ..."affix's with" are the wrong words—if used, it would be "affixes"—however, instead go with "supports both..."
Fourth paragraph: replace "values" with "elements." Next, "who was born prematurely..." should read "prematurely with a heart condition." Change the corresponding line to: "somehow survive." (Forget "miraculously...") Correct your sentence to read: "This faith also applies to Mina, who with Michael..."
Your conclusion almost sounds like it came out of a book review. If you used another source, make sure you have changed the words enough that you are not plagiarizing. Changing a few words, but still maintaining the sentence structure, is still plagiarizing. You should see how you feel about these changes and then read your edited essay aloud.
Proofread several times to check for errors. If you are in a place that uses a single quotation mark instead of the double quotation mark used in the US, make those adjustments as needed.