Hi Arielgenesis, and welcome!

From a rationalist perspective, taking things for granted is both dangerous and extremely useful. We want to preserve our ability to change our minds about things in the right direction (closer to truth) whenever the opportunity arises. That being said, we cannot afford to doubt everything, as updating our beliefs takes time and resources.

So there are things we take for granted. Most mathematics, physics, the basic laws and phenomena of Science in general. Those are ideally backed by the scientific method, which axioms are grounded in building a useful model of the world (see Making Beliefs Pay Rent (in Anticipated Experiences) ).

From my rationalist perspective, then, there are no self-evident things, but there are obvious things, considered evident by the overwhelming weight of available... evidence.

Regarding values... it's a tough problem. I personally find that all preconceptions I had about universally shared values are shattered one by one the more I study them. For more information on this, I shall redirect you to complexity of value.