I'll address this because it seems to me to encapsulate the jist of your overall post.
How do we know Election wasn't for every human to be Saved?
I think if that was God's intention the gospel would read very differently.
Namely but not limited to the fact if everyone was to be the elect, elect would lose its meaning. Which means God would have never mentioned the elect because of its definition we're his intention to save all.
Also, if all were intended to be the elect of God, God would have softened the hearts of everyone who were born first with a natural carnal mind unable to understand him.
And 2 Thessalonians 1 would not say, With flaming fire he will mete out punishment on those who do not know God and do not obey the gospel of our Lord Jesus. 9 They will undergo the penalty of eternal destruction, away from the presence of the Lord and from the glory of his strength, 10 when he comes to be glorified among his saints and admired on that day among all who have believed—and you did in fact believe our testimony. 11 And in this regard we pray for you always, that our God will make you worthy of his calling and fulfill by his power your every desire for goodness and every work of faith, 12 that the name of our Lord Jesus may be glorified in you, and you in him, according to the grace of our God and the Lord Jesus Christ.