Now back to the topic, does Jesus Christ destroy wicked humans upon his return or are they all forgiven once repentant?
This is not a question that is applicable to what happens. Christ returns and he "separates the sheep from the goats." He does some teaching and preaching and some are able to gather with him. Those who reject or ignore the Bible are subject to die at Armageddon or if they survive Armageddon, of old age and will not be granted life during the millennium. But they will come back on Judgment Day and the righteous judges will decide, based upon all factors including imperfection and the response under Christ's rule, who is worthy of eternal life or not.
So yes, it is possible to repent and in fact, some will repent at the last moment. But the Biblical ratios suggest out of the current world population, one third will die at Armageddon. Another third not chosen to live during the millennium will die of old age; these would be those not violently opposed to the kingdom. Obviously, they would provide some stability after that sharp population decrease. One third will survive into the millennium and enjoy rule under Christ until Satan is released at the end of the 1000 years.
But not to worry. The second coming occurred in 1992 so people have been "marked" for life since then. Some people who aren't even Christians will be chosen not only for the Bride Class but for the millennium. But a huge number not chosen for the millennium will still get eternal life during Judgment Day. So the millennium is a grand opportunity for the people living today.
So, you might already be marked for being in the Bride Class (1,440,000) in which case you will help administer things during the millennium. Or you will be part of the one-third who will enjoy the millennium during the rule of Christ, which will be a grand time. Or, since you're probably not a political person wanting to hold onto this current world, at the very least you will be allowed to live our your life to old age after Armageddon (79-1/2, or if special mightness, 80...sorry, I know, bad joke! ) So hope for the best.
But, once Armageddon clearly starts, repenting will not work. Everybody will repent after it starts to rain, that's a given. The thing is to repent before the destruction begins. Get marked before the angels come to destroy. Have you broken all ties with BTG (the Illuminati?). Just asking...