As a result, most people wouldn't know what righteousness was if they received it in a parcel from FedEx. Not exactly a bad condition to be in. Look then at the Bible's definition of righteousness. No, it is on account of the wickedness of these nations that the LORD is going to drive them out before you. In most of those references, righteousness is an essential part of God's character, and the righteous are those that follow God's laws.
Humans are sinners, true, but the righteous confess their sins, and learn from that.
Thus, righteousness is in part a learned trait that we pick up after learning of the grace that God extends to us in forgiving our sins. No one can get to heaven by righteous acts alone. God's law is not something that can be broken in small ways, and he'll still let us into heaven. Thus, any one sin can and will separate a human from God. Thus, our own works of righteousness in following God's law won't get you into heaven at all.