Gen 6:5-9 Yahweh saw that the evil of humanity was multiplying ion earth, and every form of the devisings of its heart was surely evil all the day. Yahweh regretted that He had made humanity on earth, and He grieved in His heart. So Yahweh said: I shall wipe out humanity that I have created, off the surface of the ground, from human unto beast, unto the creeper and unto the flyer of the heavens; for I regret that I have made them. Yet Noah, he found grace in the eyes of Yahweh. These are the genealogical records of Noah. Noah was a righteous man; he became flawless in his generations; with the One, Elohim, Noah walked.
Gen 13:13 Now the men of Sodom were wicked, great sinners against the LORD.
Exod 23:1,7 From this we gather the wicked are those that practice bad or evil works.
1Cor 6:9-11 Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God. And such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God.
Rom 1:18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth.
Rom 1:29-32 They were filled with all manner of unrighteousness, evil, covetousness, malice. They are full of envy, murder, strife, deceit, maliciousness. They are gossips, slanderers, haters of God, insolent, haughty, boastful, inventors of evil, disobedient to parents, foolish, faithless, heartless, ruthless. Though they know God's decree that those who practice such things deserve to die, they not only do them but give approval to those who practice them.
Can we call humans evil?
Yes, as scripture does. But I would not go as far as doing so to their face but only by reference. It is reserved for those who practice what is evil or unrighteous.
Luke 6:45 The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks.
1Cor 5:13 God judges those outside. “Purge the evil person from among you.”
2Thess 3:2 and that we may be delivered from wicked and evil men. For not all have faith.
2Tim 3:13 while evil people and impostors will go on from bad to worse, deceiving and being deceived.
Rev 2:2 I know your works, your toil and your patient endurance, and how you cannot bear with those who are evil, but have tested those who call themselves apostles and are not, and found them to be false.
Rev 22:11 Let the evildoer still do evil, and the filthy still be filthy, and the righteous still do right, and the holy still be holy.
While calling someone evil may sound condemnatory the Bible also indicates wicked humans can change and be seen as righteous.