You have to read Roman Chapter 14
There was a lot of sterotyping and judging going on in that book.
(Romans 14:5-9) One [man] judges one day as above another; another [man] judges one day as all others; let each [man] be fully convinced in his own mind. 6 He who observes the day observes it to Jehovah. Also, he who eats, eats to Jehovah, for he gives thanks to God; and he who does not eat does not eat to Jehovah, and yet gives thanks to God. 7 None of us, in fact, lives with regard to himself only, and no one dies with regard to himself only; 8 for both if we live, we live to Jehovah, and if we die, we die to Jehovah. Therefore both if we live and if we die, we belong to Jehovah. 9 For to this end Christ died and came to life again, that he might be Lord over both the dead and the living.
Answer to question (Who is Gideon?)
Judges 6:11 Now the angel of the Lord came and took his seat under the oak-tree in Ophrah, in the field of Joash the Abiezrite; and his son Gideon was crushing grain in the place where the grapes were crushed, so that the Midianites might not see it.
Answer to question (Who is Judges?)
Judges 2:15 Wherever they went out, the hand of the Lord was against them for evil, as the Lord had taken his oath it would be; and things became very hard for them.
Judges 2:16 Then the Lord gave them judges, as their savior from the hands of those who were cruel to them.
The book of Judges from which you have given a verse, describes about those saviors. Gideon was one of them.
Answers to question (What does 8:23 mean?)
It means God will rule over them not a human being.
Answer to question (What is Genesis?)
It is the first book of Holy Bible which tell about
1 - The birth of the world and human beings.
2 - How sin came on this world and how death came on earth.
3 - How God promised to save mankind from eternal death through the Savior He sent.