God became a man so than men can share in the divine nature; God's action was for mankind. It is an error to teach that it was for all types of men but not for mankind. Thus the Lord Jesus Christ became "a man, Christ Jesus" to mediate for all mankind because there is one God and one mediator between men and God, a man himself, our Lord Jesus Christ.
The passage says this:
(1 Timothy 2:1-7) 2 First of all, then, I urge that supplications, prayers, intercessions, and thanksgiving be made concerning all men, 2 concerning kings and all those who are in high positions, so that we may go on leading a calm and quiet life with complete godly devotion and sobriety. 3 This is good and acceptable in the sight of our Saviour, God, 4 whose will is that all men should be saved and come to know the truth. 5 For there is one God, and one mediator between God and men, a man, Christ Jesus, 6 who gave himself a ransom for all - this is what is testified to at the right time. 7 For this purpose I was appointed a preacher and an apostle - I am telling the truth, I am not lying - a teacher of nations in faith and truth.
Thus Christ mediates for all man, and all are ransomed by him as the scripture says.