Your interpretation of Psalm 12:6-7 is wrong. Read the whole psalm, not just the two verses. Then you will see what the subject is. God keeps His children safe—for all eternity, not just this generation. That protection is something you can rely on because the Creator personally makes that commitment to you. It's a promise you can claim.
The immediate context of verse 7 is God’s pure words (verse 6) being preserved forever. But I am not going to ignore the rest chapter by any means. I also agree that God’s people is included in being preserved forever, too. It is talking about seeing they are both the context. We would not have faith if it was not for the Bible. Jesus says heaven and earth shall pass away but my words shall not pass away.