The person wPeople Who tTaught mMe sSomething iImportant | Edited

Your friends are plural --> “people”
If this is a title, every word except for articles and some prepositions should be capitalized (except for the first word which is always capitalized)
You can find title capitalization rules online

I learned this about a few months ago, quite recently.quite recently (a few months ago)

“A few” is already vague so adding “about” is redundant

However,with there had been some people who helped me to understand itelp of some very kind/special/[uplifting adjective of your choice] people.

“However” indicates contrast/contradiction with the previous statement. This epiphany being recent and needing the help of others to understand aren't contradictory so “however” is not appropriate here
Since this part doesn't really connect to the ideas around it it makes the most sense to incorporate it into the previous sentence as an addition rather than make it its own separate thought. Since these people helped you, it would also be customary to describe them positively (eg. “Thanks to my amazing support system, I became a world-class singer.”).

As I entered adolescence, I had many insecurities about myself.was insecure

Sometimes too many words is a bad thing. When it comes to insecurities, we usually don't use the words “have”/”hold” with a specific description of the insecurities. For example, I could say “she is insecure” or “she had a lot of insecurities” or “she is insecure about her musical talents”, but “she has insecurities about her musical talents” sounds awkward.

Aabout my appearance, personality, etc.

Matching capitalization with previous correction

I was too blinded by [insecurity, jealousy, whatever emotion you want to put here] to notice my positive traits.

Not bad as is but since you are not talking about literal blindness it would be good to say what was getting in the way of you seeing your positive traits

When I turnedwas 15, I finally started breaking down the wall of lowbegan to build my self-esteem.

Turning 15 is a specific, timely action - at midnight on your 15th birthday, you turn 15 and that's it. Because of that, saying “when I turned 15” somewhat implies that a specific event on your 15th birthday caused this change. “Was 15” is better in my opinion because “was” is a state - it says that at some point while you were 15 this change occurred, but it wasn't triggered by you turning 15 and it wasn't necessarily a sudden change
Breaking down a wall is a bit of a strange analogy if you're not going to expand upon it
Also, the use of the word “low” and “wall” in the same sentence undermined your meaning a little. I know you weren't using low to refer to the wall you're breaking down but when I read it my brain made the association between low and wall and I can't say if that is a connection only I made or if most readers might think the same thing.

With their support, I observrecognized my own worth and somemy unique traits I have.

“Observe” is more factual while “recognize” has the nuance that these traits were always there but it just took you some time to see them. Maybe the more factual, distant tone is what you wanted but I suspect “recognize” serves your purpose better

They taught me that self-love isn't selfish.

GREAT line :)

AThey showed me that there is a gigantic gap lies between confidence and vanity, and my friends have shown me that difference.

Less wordy

Confidence allows you to broaden your horizons, while vanity crippleprevents you from seeing anything beyond yourself.

Cripple as a verb is used to describe being handicapped in a literal or more figurative sense (eg.
”his excellent brain was crippled by his aversion to studying”). It's not exactly incorrect here but it's also not the best choice of word in this case. “Prevents” or “keeps” (informal) works better here. As a noun, it is a derogatory term for people with disabilites so I would use it very carefully.

They have given me such a gift -fted me the freedom to walk around with my head held high and to live my life without seeking others’ approval.

Of course sSome will.

But that does in't matter?.

Personal preference, what you have is still right

No.

Match precious correction

As long as I am happy withand living my life the way I feel is healthiest and happiest, that’s what truly matters.

Happy and happiest in the same sentence is redundant

The pA Person wWho tTaught mMe sSomething iImportant | Edited

Life is a philosophy, and as long as we are still breatheing we have to face whatever fate throws at us.

One of the most important lessons that I've learned is that of self-love, which I believe is the key to happiness.

I learned this aboujust a few months ago, quite recently.

I don’t know why but about a few months ago doesn’t sound correct to me. About a month ago works fine, although I can’t explain why.

However, there hads been some people who have helped me to understand it.

Since it is something that happens in the past and not the past of the past, the pluperfect cannot be used

As I entered adolescence, I had manDuring my teenage years, I was very insecuritiese about many parts of myself.

Entered adolescence sounds extremely formal and old-timey.

AInsecurities about my appearance, and my personality, etc for example.

I was too blind to notice any of my positive traits.

When I turned 15, I finally started breaking down the wall of lowto work on my self- esteem.

Break down the wall of something is not an expression in English as far as I am aware of.

One of the biggest helping factors was my friends.

With their support, I observedcould finally see my own worth and some unique traits that I have.

Observe means to study and look at something closely. In this case I would just use see.

They have given me such a gift -: the freedom to walk around with my head heldup high and live my life without seeking others’ approval of others.

Of course some of them will.

As long as I am happy with living my life in the way that I feel is healthiest and happiest,makes me the happiest because that’ is what truly matters.

P.S. : I thought that some information was unnecessary + I rephrased particularsome sentences.

The personople who taught me something important | Edited

My recommendation for consistency with the rest of the essay; you say it is multiple friends

Life is alived according to your philosophy, and as long as we breathe, we have to face whatever fate throws at us.

"Life is a philosophy" doesn't quite feel like it works to me. The meanings are too different to equate them like that. I suggest the above.

I learned this about this a few months ago, quite recently.

However, there hadve been some people who have helped me to understand it.

Present perfect tense "have been," "have helped" - they helped you in the past and are continuing into the present

When I turned 15, I finally started breaking down the walls of low self-esteem.

We usually use the plural "walls" in this idiom

A gigantic gap liesThere is an enormous gulf between confidence and vanity, and my friends have shown me that difference.

What you had works, but this sounds a bit more natural/idiomatic

As long as I am happy with living my life the way I feel is healthiest and happiest, that’s what truly matters.

P.S. : I thought that some information was unnecessary + I rephrased particular sentences.