Sergio, you are asking question(s) that every human being benefits from assessing throughout their life. And accepting the humbling effect.
Pride is how humans supposedly reasoned, and continue to reason, things to a conclusive result. Obviously, there is nothing at fault with reasoning, and taking realistic pride in the process, it's when we decide a "belief" is the end point, a finality. And then teach, argue, persuade, manipulate, convince others of the same, without compromise.
Few things "make sense" exactly the way we insist they must. The average human is desperate to draw conclusions they can "bank on" at various stages of their life experience. This is based in fear, fear of the unknown or not "easily" understood. And that is what fear is based on, lack of knowledge, refusal to gain knowledge, and the like.
Most have been taught "to take pride in things, ideas and their selves," while over-the-top pride leads to conflict and disagreement. There's nothing amoral with having pride in one's heritage, team or "belief," until it results in separation of individuals and groups.
Relax with your current thoughts and I can assure you, you will gain enlightenment of a sort. Remember you are only being skeptical about things others have "reasoned" to conclusions, probably influencing your own ideas and beliefs, and these things are always open to evolution and clearer understanding. Even though you may have accepted or been taught they aren't.
You mentioned "basic assumptions." When you honestly look at that phraseology, you realize it's simply guess-timating.
Human beings are what we were, "Human Becomings" are what we can be.