It does not mean everyone is saved “to” the kingdom- but theirs sins have been paid for.
Yes, that's sort of how I see it too. Jesus' sacrifice has paid the redemption price for everyone, so everyone's sins will be forgiven and God is justified in resurrecting everyone to life again. To gain eternal life we must believe in Jesus and accept his sacrifice. Christians believe in this Gospel age, and will be resurrected perfect and given immortality, just as Jesus was at his resurrection. Everyone else will be resurrected in the second resurrection, and will learn to believe in Jesus during the Millennial Age - those that don't believe and prefer to side with Satan will perish, and not have eternal life (an eternal punishment, with no hope of another resurrection).
1 John 2:2 (WEB):
(2) And he is the atoning sacrifice for our sins, and not for ours only, but also for the whole world.
John 3:16-17 (WEB):
(16) For God so loved the world, that he gave his one and only Son, that whoever believes in him should not perish, but have eternal life.
(17) For God didn’t send his Son into the world to judge the world, but that the world should be saved through him.
However, the opportunity to become members of the body of Christ, and to have a part in the first resurrection to spirit beings, having a home in heaven and sharing in Jesus' reign over the rest of mankind who will be resurrected as humans again, that requires God to call who He chooses, during this Gospel Age (before the first resurrection). Jesus said, John 6:44-45 (WEB):
(44) No one can come to me unless the Father who sent me draws him, and I will raise him up in the last day.
(45) It is written in the prophets, ‘They will all be taught by God.’ Therefore everyone who hears from the Father, and has learned, comes to me.
Those who don't believe are no different than those that do, it's just that God has called whoever He decides to call, and draws them to Jesus, giving them faith (a free gift from God). Ephesians 2:4-10 (WEB):
(4) But God, being rich in mercy, for his great love with which he loved us,
(5) even when we were dead through our trespasses, made us alive together with Christ (by grace you have been saved),
(6) and raised us up with him, and made us to sit with him in the heavenly places in Christ Jesus,
(7) that in the ages to come he might show the exceeding riches of his grace in kindness toward us in Christ Jesus;
(8) for by grace you have been saved through faith, and that not of yourselves; it is the gift of God,
(9) not of works, that no one would boast.
(10) For we are his workmanship, created in Christ Jesus for good works, which God prepared before that we would walk in them.
2 Timothy 1:9-10 (WEB):
(9) who {God} saved us and called us with a holy calling, not according to our works, but according to his own purpose and grace, which was given to us in Christ Jesus before times eternal,
(10) but has now been revealed by the appearing of our Savior, Christ Jesus, who abolished death, and brought life and immortality to light through the Good News.