Human beings are believed to be innately good. Every individual is born with an inclination towards goodness, a natural state that has been implanted in every soul by God. Children are thus born sinless, although every child will have their own unique characteristics and personality and their upbringing and experiences will often shape their response to situations. Muhammad said, "Every child is born in a pure state of nature (fitra)." (Muhammad).
Furthermore, every person has within them the ability to distinguish between right and wrong, Muhammad also said:
"Righteousness is that which makes the heart and the soul feel tranquil, wrongdoing is that which wavers in the soul, and moves to and fro in the chest even though a legal opinion may have been given in its favour."
In other words, when something is good or right, you feel at ease with that decision, however when something is wrong or unjust, although people may tell you it's fine, in your heart you will always feel it to be wrong. But human life is complex and we will often face tendencies that pull us in different directions - from our ego, greed or another negative influence within. Muslims believe human beings were given freewill so they could choose how they live their life, and whether they follow their innate goodness or choose to live otherwise.