In your religious scenario it is YOUR God that made sin a thing. YOUR God is accountable for what it created. You seem to think this is as good as it gets, and we should just deal with it. Any decent human could do a better job. Get rid of mosquitos, deadly virus and bacteria. Get rid of birth defects, and cancers. Do we really need earthquakes? Do we need tornados and hurricanes? It's as if your God hates people.
No, the biblical God did not create sin. Sin is not a created thing. Sin is the absence of God’s holiness, perfection, and goodness. People commit sin by their actions which fall short or are contrary to God’s will, laws, and wisdom…
…for all have sinned and fall short of the glory of God. Romans 3:23
Once humans sinned the curse of sin impacted all creation causing all the negatives you mentioned; mosquitoes, diseases, tornadoes, earthquakes, etc.
…For we know that the whole creation groans and labors with birth pangs together until now. Romans 8:22
So, the need for a new heaven and earth free of sin and it’s damaging impact, an eternal world filled with human beings who have deliberately acknowledged their propensity to sin, need to be saved by God, and have a transformed eternal life.
…And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what
is that good and acceptable and perfect will of God.
Romans 12:2