There are some minor grammatical, stylistic, and phrasing issues:

> From the dawn of times, people were writing. We have written using symbols, like in Ancient Egypt. And we have written using letters, like in Renaissance times

"From the dawn of time" is somewhat of a cliché in starting an argument, adding the "s" to "time" makes it a malapropism. This isn't a great way to start a post on the importance of writing. I would generally expect this to be phrased "Since the dawn of time". You, like many writers, have a tendency to over-signify the independence of clauses, leading to a bit of turbulence. Your second and third sentences could be phrased:

"We have written using symbols, like in Ancient Egypt, and we have written using letters, like in Renaissance times"

I'm not going to be a stickler about the "sentences shouldn't start with 'And'". This couplet isn't wrong per se, but the lack of specificity in your writing doesn't exactly scream "I know the history of the written lanuage!" Don't be afraid to be specific. In both the cases of Egypt and the Renaissance there were earlier cases of symbol-based and letter-based writing systems. Researching, naming them, and giving the reader that extra bit of context will make your writing more engaging.

There are also tense conflicts between these two sentences: one is firmly rooted in the past tense while the other lands in the present perfect tense. This is a big ol' nitpick but once you start really paying attention to tense you start to notice that tense-disagreement can make writing sound disjoint. One way this could be rephrased or improved upon is to focus on tense agreement and be more direct in what you're saying:

"Since at least 3400 years ago, people have used writing to communicate ideas. Ancient Egyptians and Mesopotamians had complex language systems that revolved entirely around the use of symbols. As language evolved, words and letters gave writers a near-infinite sandbox of concepts and tools with which to communicate. By the time of the Greeks, alphabetic languages like Aramaic, Hebrew, and Sanskrit were used the world over to preserve and communicate ideas."

A few more examples:

This is a big misconception, we all fall for. -> This is a big misconception that many software engineers fall for. (comma overuse) (unclear "we") (overgeneralization in using "all")

One simple way to write more–is to approach design reviews in a different way. Instead of hating them, and doing them like a homework assignment, try to approach them with enthusiasm -> One simple way to write more is to approach design reviews in a different way. Instead of hating them or treating them like a homework assignment, try to approach them with enthusiasm (hyphen misuse, comma overuse)

One last advice–abolish the copy-paste. So many developers, whom I mentored, simply copy-paste everything. Code snippets, function declarations, etc. I know how to initialize a git repository, because I do it by hand every time -> One last piece of advice: abolish the copy-paste. Many developers I have mentored simply copy-paste everything from code snippets to function declarations. I know how to initialize a git repository because I do it by hand every time. (comma overuse, hyphen misuse, unnecessary sentence snippet).

I would like to echo the other commenter that I really agree with the message here, and think it's illustrative that you're getting feedback on your writing after posting it here. If you never write, nobody will ever have the chance to give you feedback. Keep it up!