it is that a relationship without respect is nothing, a conversation without respect is nothing.

Agreed, mutual respect is the foundation of understanding. Without it, there is little reason to interact because it will lead nowhere productive.

The important thing is to put on the shoe of the other person to try to understand why he thinks in one way or another.

Precisely. Compassion and empathy are vital.

Who do not accept comments from others and resort to insults to feel winners.

This is the sign of a child. Many people think they are adults but in mentality they remain children, often into their old age. This is because aging in the sense of declining in energy is a passive process and somewhat of a given, but aging in the sense of maturing and gathering wisdom is a passive-active process: it requires our consent and effort that we actually progress as conscious beings.

In reality, the real gain is to learn from the opinions of others, to take their visualization in order to work on improving ours.

This is true power WITH people, instead of power OVER people.

The truth is very relative, depends on a very subjective view of the world and situations ...

To untangle this we have to realize the word "truth" can represent different things. When people say truth is subjective, they refer to "your truth/my truth" which is not really the truth but only opinions and beliefs, all of which are somewhat true and somewhat false.

THERE IS NO ABSOLUTE TRUTH

In my view, this is an absurd statement from an ontological level. Although this statement has become quite popular in the fallacious ideologies of radical relativism promoted in modern society to confuse and weaken people, it represents a nonsensical assertion that reality can be other than It Is.

If it is granted that "something exists," no matter what that something is (opposite of nihilistic conception) then the exact opposite of your statement must be concluded. "ABSOLUTE TRUTH" is the only thing that is real because it represents veracities that are unimpeachable, like the laws of quantum physics. (which humans comprehend only 0.0000001% of)

What I think you meant was that "no human is the sole owner of truth" meaning that all of our fragments of the Truth are part of the macrocosmic dynamo that is our reality. And although absolute Truth is radically real beyond all else, it is only knowable to humans in parts. I'm being a little semantically picky here, but I think it's important.

Everyone believes in their truth, in their world, but is surrounded by thousands of people in their worlds and the only way to progress is to coexist.

Again, I agree, but would call the amalgamation of all these billions and trillions of worlds "Absolute Truth" or more generally, "The Absolute." @darkfemme