The word "world" in the Bible means humanity. Such as, "God so loved the world" John 3:16.
Not exactly. Matt16:26, 1Tim6:7 and Acts17:24 do not use “kosmos” as equivalent to “humanity” at all. Rather, the context tells you what it means.
John12:19 The Pharisees therefore said among themselves, “You see that you are accomplishing nothing. Look, the world has gone after Him!”
This verse doesn't mean that everyone in the world was following Jesus – if you took a moment to reflect, you would notice that the Pharisees were not included in this “world” and likely none of the people who lived thousands of miles away on other continents at that point either.
All they meant by “world” was that all kinds of people were following Jesus – like many of the Jews and also the Greeks mentioned in v20.
John17:9 “I pray for them. I do not pray for the world but for those whom You have given Me, for they are Yours...20 “I do not pray for these alone, but also for those who will believe in Me through their word...
This verse doesn't mean that Jesus refused to intercede for everyone in the world. He is obviously praying not only for those who believed at that time, but also those who would believe in the future – even today. (And not just in a “might/maybe/hope for the best” optimism but certainty of those who definitely “will” believe.) He prays that we would be united and protected from the evil one – I believe that God knows the future and that Jesus could have prayed for me by name had He wanted. OTOH, the subset of humanity excluded from this prayer would logically be those who did not believe and who never will believe to the end of time. You could call this subset of humanity the “world of unbelievers.”
John3:16 For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life. 17 For God did not send His Son into the world to condemn the world, but that the world through Him might be saved. 18 He who believes in Him is not condemned; but he who does not believe is condemned already...
You like the first verse here but never get to the rest of the chapter (i.e. the context). Jesus was not sent into the world to condemn the “world” (presumably the same “world” that God loves in v16) and yet v18 says that unbelievers are condemned already. Is the Father condemning the same group of people that the Son will not condemn? You really think the Father and Son are working in opposition and not on the same page if it will salvage your misreading of v16? Or would it just make too much sense if the "unbelievers" here in John 3 are not included in the subset of the "world" in this passage?
From a human perspective, it is true that anyone may come and every single one of those who comes will be accepted. There is no mystical Calvinistic “elect” who refuse to believe within space and time that Jesus is Lord and Savior. Any leader of ISIS will certainly be saved if they call on the Lord in faith and repentance. The issue for Calvinists is “why do we choose what we choose?” I do not believe that people choose randomly (you misname it to say "freely") – so in order for someone to make different choices, they would need to see the world differently (which is the point of the beginning of John 3).
But there is no “whosoever” here in the Greek. There is no uncertainty in the passage at all. From God's perspective, He declares the end from the beginning and accomplishes all that He intends (Isa46:10-11) even if you implicitly deny God's perfect knowledge of the future. There is a promise in John 3 for all those who believe, and secondarily, a curse for those who don't believe (v36 He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him). If you want to see the “reverse image” of this passage, Psalm 2 is directed to unbelievers with only a side reminder to believers that they have nothing to fear. If you can't teach your version of “God loves the world” with Psalm 2, then your Bible might be broken (or else you need to stop and check your theology.)